Aliphatic hydrocarbon possess straight chains. And aromatic hydrocarbon contains a aromatic chain like a benzene ring
						

							
Aliphatic compounds can be saturated, joined by single bonds (alkanes), or unsaturated, with double bonds (alkenes) or triple bonds (alkynes). Besides hydrogen, other elements can be bound to the carbon chain, the most common being oxygen, nitrogen, sulphur, and chlorine.
they may be alkane , alkene , or alkynes . 
AROMATIC have a pleasant odour , hence , they are called so . 
they are found to contain benzene ring . 
they have 2 types – benzenoids and non – benzenoids . on the besic of contain of benzene ring or not . 
its planer , complete delocalisation of pie – electrons in the ring . 
HOPE IT CLEARS 
ALL THE BEST ..
 
						

							Aromatic hydrocarbon is a closed ring structure whereas aliphatic is not closed ring but a straight chain structure
						

							
Aliphatic compounds are the straight chain compounds where as aromatic are the ring structure compounds.
ex:butane and toulene respectively.
further there are saturated and unsaturated compounds.Alkanes,alkene,alkynes are aliphatic compounds inwhich alkanes are saturated ,,remaining are unsaturated.All the aromatic are unsaturated.
 
FLAME TEST
Aromatic give sooty flame whereas aliphatic give non-sooty flame.
 
 
						

							
alidhatic compounds are open chain structure and aromatic compounds are closed ring resonance structure