Do trigger.newMap and trigger.oldMap have the same keySet() in apex after update triggers?

Question

My potential use case by knowing the answer to this question would be, if I'm working with a legacy code and I can't make modification to the method signature and I only have access to trigger.new and trigger.oldMap. Let's say I'm working in a contact trigger after update context. If I pass oldMap.keySet() to a helper method, for example to query out a list of tasks related to that set of contact ids, is it the same as if I have passed newMap.ketSet() to that same method? would it return the same list of tasks? Thanks!

Answer 1

Short answer is: Yes, both maps have the same key set.