What is the difference between P3e and P6?

I am a P3 user, and have the option to go to P6 or P3e.

i am leanign towards P3e as it will be more compatible with clients who i work with to allow ease of plan transfer.

My questions are:

is P6 the newest version of P3 (ie updated V5 of P3)? From what i can gather is it web based.

How is P3e different to P6?

what is more likely to be the tool that lasts the longest, ie will P6 replace P3e eventually or vice versa.

Thank you for all you help and advice in advance.

Dave