hi there
hydrocarbons are compounds with Cand H atoms but once you have a halogen atom such as Cl, F , Br or I its called halocarbons.
alcohol has an OH group where the O is attached directly to the H if you have C=O then its not alcohol its either ketone ot aldehyde.
for esters its R-CO-R' where the carbonyl group is between 2 R groups it doesn't matter if they are similar or differ.