Were The Jedi The Guardians Of Peace For Over A 1000 Years Or A 1000 Generations?

I'm confused on what the actual length in the Star Wars lore of how long the Jedi were the guardians of peace and Justice of the old republic.

In the original film Obi Wan to Luke states for over a thousand generations. This would be starting about the time of Knights of the Old Republic which makes sense.

However in Episode II, Palpatine states it to be a 1000 years which I've noticed some people here use.

Which is it?