Je suis passé devant Michelle. | Il est arrivé avant lui.

Bonjour VitN,

I'm going to take the example sentences in the post title and run with those, and hope that while I'm explaining their respective meaning that things will become clearer for you.

• Il est arrivé avant lui. (He arrived before him.) - Here, ‘avant’ (and ‘before’) refer to time, i.e. that he arrived earlier.
• Je suis passé devant Michelle. (I came before Michelle.) - Here, ‘devant’ (and ‘before’) refer to being ahead of someone or something in an order of arrangement. For example, we might be talking about a series of interviews or tests with a group of people and the above sentence means that ‘I was ahead of Michelle’ either in order of people or results.

Of course, the sentence without context in English could mean something else, i.e. ‘I arrived earlier than Michelle’, or ‘I stood in front of Michelle’ but given the French translation and the section title, we can infer the meaning as ‘to be ahead’.

I hope this helps!

   -   Mitchell