Bonjour Marc, comment vas-tu aujourd'hui?
They are very similar, but aim and target are usually used in context with guns or sport.
Any of these three are correct:
The objective of this training course is to increase my knowledge.
The purpose of this training course is to increase my knowledge.
The aim of this training course is to increase my knowledge.
In a sport context:
The Olympic archer shot his arrow at the target.
The hunter decided that the big deer would be his target.
Your sales target should be to sell two products every hour.
You can also use aim and target as verbs.
Be careful when you aim your gun.
When you advertise, make sure you target the audience that you want.
J'espère que c'est utile. :-)