The difference between Canninzaro’s and Aldol condensation lies in the presence or absence of

(alpha)-hydrogen.
Aldol-Condensation -
Aldehydes and ketones which contains at least
one alpha-hydrogen undergo self-condensation in the presence of dil.alkali and form beta-hydroxy aldehyde known as aldol or beta-hydroxy ketone called as ketol respectively.
CH3CHO + CH3CHO -----------> CH3CHOHCH2CHO
If this alpha hydrogen is absent in aldehyde or ketone like formaldehyde,benzaldehyde or benzophenone,aldol condensation is not possible.
Canninzaro’s Reaction –
This reaction is given by aldehyde which do not contain alpha-hydrogen.Aldehydes like formaldehyde or benzaldehyde undergo self-oxidation and reduction on treating with conc.alkali.(KOH).One molecule is oxidised to acid and another is reduced to alcohol.
HCHO + HCHO ----------> CH3OH + HCOOK