May I help you or can I help you?

"Would" and "will" is about the same thing so you're asking the same thing twice: Whether I will help or not. Helpful?

The Word "would" tends to convey a question of willingness to perform a task.

Ex: Would you help me if you had the time?

The Word "will" is asking for assistance for a task.

EX: Will you help me as I need to get this task done right away?

Slight but noticeable differences.