What's the difference between 'ceux' and 'lesquels' ?

Question

I've heard that both ceux(and all of its forms) and lesquels(and all of its forms) means the one. So, how do you differentiate? For example: Eva aime mes biscuits mais déteste ceux de sa tante.

Accepted Answer

Hi Tibor,
The following depending upon context:-
Ceux  --  the ones / those / those ones
Lesquels -- which / who 
Recommend you have a look at the Wordreference site    https://www.wordreference.com/
This will help you in the future with questions like this.
Hope this helps.
Jim

Answer

Grammatically speaking, "ceux" is a demonstrative pronoun and "lesquels/lesquelles" is a relative pronoun.
Les gens, parmi lesquels tu te trouves, sont des amis. -- The people, among whom you find yourself, are friends. In this example, "lesquels" is a relative pronoun substituting for "les gens".
Quels livres  vous préférez? Ceux-ci ou ceux-là? -- Which books do you prefer? These or those? This shows clearly that ceux is used as a demonstrative pronoun. It can never stand for a relative pronoun.