By neutral FeCl3 only allylic and phenol can be distinguished.
By NaHSO3 and 2,4-DNP: ketone and aldehyde both can give test.
Ketone and aldehyde can be distinguished by Tollen's reagent, Fehling's solution and Schiff's reagent. CH3COCH3 (ketone) and CH3CH2CHO (aldehyde) can be distinguished by Tollen's reagent. CH3CH2CHO reacts with Tollen's reagent to give silver mirror while CH3CH2CHO+Ag2O→ΔCH3CH2COOH+2Ag
Silver mirror CH3COCH3+Ag2O→Δ No reaction