Italian grammar question

I'm confused as to the difference between the past participle and gerund in Italian. I thought in English they were the same thing, but in Italian they're apparently slightly different. I know in French it's just a matter of adding "en" to the present participle to form the gerund.

For example in English it would be "having"

In Italian, the past participle is avente and the gerund is avendo. What's the difference?

Or the same thing with "doing" and facente and facendo, respectively.

I believe the present participle (I assume that's what you mean) is used as an adjective, and the gerund is used verbally (to form tenses and so forth). In English though the forms are the same in both. This is an example I thought about.

A flying plane (flying here is used as an adjective)

A plane flying overhead (Here flying is used as a gerund)

present participle: avente
past participle: avuto
gerund: avendo

Present participles are used as pure adjectives: evidente (evident) or as nouns: amante (lover).

k thanks, and sorry yeah i meant present participle not past