Heskey has scored twice and has had two assists in the three games since Houllier has taken charge, and the Frenchman thinks that only lack of confidence stops him from being as good as Drogba.
He said: “Drogba is a fantastic centre-forward, probably the best in the world. He's got everything. He can score by himself, be on the end of crosses, head the ball, take free-kicks, and he works very hard for the team.
“But we have a centre-forward who can do the same. Emile is strong, quick, powerful. It's mainly a matter of faith in himself.”
Last season Drogba scored 37 goals to lead Chelsea to their first double, whereas Heskey managed just five goals in 42 appearances.
But Houllier thinks if Heskey starts to have more belief in his ability, a better season will lie ahead.
He said: “In terms of skill, he does things in training that you would be amazed and surprised [to see]. I think Emile forgets sometimes how good he can be.”
Villa host Chelsea on Saturday in what will be Houllier's biggest test since taking charge at Villa Park.
Drogba is out of the match with a virus.