Is there good posts that explains it? I heard high INT and WIS are better for resisting spell cast at you in PvE but what about PvP?

Examples:
- Is being a fire giant (instead of a drow) a disadvantage at casting a spell on an elf? (talking about casting, not resisting the spell)
- Does level difference (L40 drow vs L46 drow) affect chances of landing/resisting a spell?

As mentioned above, I heard saves we're based on INT and WIS, but I recently red it was different for poison, scourge and plague wich are based on CON... is this true?