a.    Genotype and Phenotype.
Genotype
  | Phenotype
  | 
The internal genetic makeup or appearance of an organism is called genotype.
  | The external appearance of an organism for a contrasting characteristic is called phenotype.
  | 
| Parental characteristics can be found in genotype. | Parental characteristics cannot be found 100% in phenotype. | 
| It is expressed in letters. | It is expressed in words. | 
b.    Dominant characteristics and Recessive characteristics.
Dominant characteristics
  | Recessive characteristics
  | 
| The characteristics which are prominent and appear in successive generations are called dominant characteristics. | The suppressed characteristics which cannot be expressed in successive generations are called recessive characteristics. | 
| Dominant characteristics are seen over recessive. | Recessive characteristics remains hidden. | 
c.    F1 generations and F2 generations.
F1 generations
  | F2 generations
  | 
| The generation obtained by crossing two parental stocks is called F1 generations. | The generation obtained by crossing two parental stocks of F1 generations is F2 generations.
  | 
| The parents of F1 generation have pure genotype. | The parents of F2 generation does not have pure genotype.
  | 
| It is also first filial generation. | It is also second filial generation.
  | 
d.    Monohybrid cross and Dihybrid cross.
Monohybrid cross
  | Dihybrid cross
  | 
| The cross involving only one pair of constracting characteristics is called monohybrid cross. | The cross involving two pair of constracting characteristics is called Dihybrid cross.
  | 
| Here, off springs having phenotypic ratio of 3:1 are produced in F2 generation. | Here, off springs having phenotypic ratio of 9:3:3:1 are produced in F2 generation.
  |