Difference Between - Science Comparisons
The exam favourite "distinguish between" questions, answered clearly. Side-by-side comparison tables for Class 11 & 12 Physics, Chemistry, Biology and Maths - each with a one-line answer, a full table, and FAQs.
⚛️ Physics
Speed vs Velocity
Speed is a scalar quantity that measures how fast an object moves (magnitude only); velocity is a vector quantity that measures how fast and in which direction it moves.
See the difference → ⚛️ PhysicsDistance vs Displacement
Distance is the total length of the path travelled (scalar, always positive); displacement is the shortest straight-line distance from start to end, with direction (vector).
See the difference → ⚛️ PhysicsMass vs Weight
Mass is the amount of matter in an object (scalar, constant everywhere, measured in kg); weight is the gravitational force on that mass (vector, changes with g, measured in newtons).
See the difference → ⚛️ PhysicsScalar vs Vector
A scalar has only magnitude (e.g. mass, speed, temperature); a vector has both magnitude and direction (e.g. velocity, force, displacement).
See the difference → ⚛️ PhysicsAC (Alternating Current) vs DC (Direct Current)
Alternating current (AC) periodically reverses its direction and is used for power transmission; direct current (DC) flows steadily in one direction and is used in batteries and electronics.
See the difference → ⚛️ PhysicsSeries Circuit vs Parallel Circuit
In a series circuit components are joined end-to-end so the same current flows through all of them; in a parallel circuit components are joined across common points so the same voltage appears across each branch.
See the difference → ⚛️ PhysicsConvex Lens vs Concave Lens
A convex (converging) lens is thicker in the middle and brings light rays together to a focus (positive focal length); a concave (diverging) lens is thinner in the middle and spreads light rays apart (negative focal length).
See the difference → ⚛️ PhysicsReflection vs Refraction
Reflection is the bouncing back of light from a surface into the same medium; refraction is the bending of light as it passes from one transparent medium into another due to a change in speed.
See the difference → ⚛️ PhysicsLongitudinal Wave vs Transverse Wave
In a longitudinal wave the particles of the medium vibrate parallel to the direction of wave travel (compressions and rarefactions); in a transverse wave the particles vibrate perpendicular to the direction of travel (crests and troughs).
See the difference →🧪 Chemistry
Ionic Bond vs Covalent Bond
An ionic bond forms by the complete transfer of electrons from a metal to a non-metal (creating ions); a covalent bond forms by the sharing of electron pairs between non-metals.
See the difference → 🧪 ChemistrySigma (σ) Bond vs Pi (π) Bond
A sigma (σ) bond forms by head-on (axial) overlap of orbitals and is stronger; a pi (π) bond forms by sideways (lateral) overlap of p-orbitals and is weaker.
See the difference → 🧪 ChemistryOxidation vs Reduction
Oxidation is the loss of electrons (or gain of oxygen / loss of hydrogen); reduction is the gain of electrons (or loss of oxygen / gain of hydrogen).
See the difference → 🧪 ChemistryAldehyde vs Ketone
In aldehydes the carbonyl carbon is bonded to at least one hydrogen and sits at the end of the chain (–CHO); in ketones the carbonyl carbon is bonded to two carbon atoms and sits within the chain.
See the difference → 🧪 ChemistryEndothermic Reaction vs Exothermic Reaction
Endothermic reactions absorb heat from the surroundings (ΔH is positive, surroundings cool); exothermic reactions release heat to the surroundings (ΔH is negative, surroundings warm).
See the difference → 🧪 ChemistrySN1 Reaction vs SN2 Reaction
SN1 is a two-step reaction that goes through a carbocation intermediate, is favoured by tertiary substrates and gives racemisation; SN2 is a single-step reaction with a transition state, is favoured by primary substrates and gives inversion of configuration.
See the difference → 🧪 ChemistryAcid vs Base
An acid donates hydrogen ions (H⁺), tastes sour and has a pH below 7; a base accepts H⁺ (or donates OH⁻ ions), tastes bitter, feels soapy and has a pH above 7.
See the difference → 🧪 ChemistryElement vs Compound
An element is a pure substance made of only one kind of atom that cannot be broken down into simpler substances chemically; a compound is a pure substance made of two or more elements chemically combined in a fixed ratio.
See the difference →🔬 Biology
Mitosis vs Meiosis
Mitosis produces 2 genetically identical diploid cells for growth and repair, while meiosis produces 4 genetically different haploid cells (gametes) for sexual reproduction.
See the difference → 🔬 BiologyDNA vs RNA
DNA is a double-stranded molecule with deoxyribose sugar and the base thymine that stores genetic information; RNA is usually single-stranded with ribose sugar and the base uracil, and carries out protein synthesis.
See the difference → 🔬 BiologyProkaryotic Cell vs Eukaryotic Cell
Prokaryotic cells have no membrane-bound nucleus or organelles and are small (1–10 μm), while eukaryotic cells have a true nucleus and membrane-bound organelles and are larger (10–100 μm).
See the difference → 🔬 BiologyPlant Cell vs Animal Cell
Plant cells have a cellulose cell wall, chloroplasts and a large central vacuole; animal cells lack these but have centrioles and only small vacuoles.
See the difference → 🔬 BiologyArtery vs Vein
Arteries carry blood away from the heart under high pressure and have thick muscular walls; veins carry blood towards the heart under low pressure, have thinner walls and valves to prevent backflow.
See the difference → 🔬 BiologyXylem vs Phloem
Xylem transports water and minerals from roots to leaves through mostly dead cells (one direction, upward); phloem transports food (sugars) throughout the plant through living cells (both directions).
See the difference → 🔬 BiologyMitochondria vs Chloroplast
Mitochondria release energy by breaking down glucose in cellular respiration (present in all aerobic cells); chloroplasts trap light energy to make glucose in photosynthesis (present only in green plants and algae).
See the difference → 🔬 BiologyRod Cells vs Cone Cells
Rod cells enable vision in dim light and detect only shades of grey (black-and-white); cone cells enable vision in bright light and detect colour.
See the difference → 🔬 BiologyEndocrine Gland vs Exocrine Gland
Endocrine glands are ductless and pour hormones directly into the blood; exocrine glands have ducts that carry their secretions to a specific surface or cavity.
See the difference → 🔬 BiologyInnate Immunity vs Acquired Immunity
Innate (non-specific) immunity is present from birth and responds the same way to all pathogens without memory; acquired (specific) immunity develops after exposure, is pathogen-specific and has memory.
See the difference → 🔬 BiologySystole vs Diastole
Systole is the contraction phase of the heart when blood is pumped out of the chambers; diastole is the relaxation phase when the chambers refill with blood.
See the difference → 🔬 BiologyC₃ Plants vs C₄ Plants
C₃ plants fix CO₂ directly via the Calvin cycle into a 3-carbon compound (3-PGA) and undergo photorespiration; C₄ plants first fix CO₂ into a 4-carbon compound (OAA) using Kranz anatomy, minimising photorespiration.
See the difference → 🔬 BiologyAerobic Respiration vs Anaerobic Respiration
Aerobic respiration uses oxygen to completely break down glucose into CO₂ and water, releasing a large amount of energy (~38 ATP); anaerobic respiration occurs without oxygen, gives incomplete breakdown and releases far less energy (~2 ATP).
See the difference →