The two are more alike than they'd like to admit. Similarities are that they are dormant at first, you don't see their power or traits when they're first created or born. At this point, a Peacekeeper can't sense a Reality Ripper if one or the other is dormant.

Example: Cyber didn't attack Titus because Titus wasn't a Peacekeeper yet. Titus didn't sense Cyber because his abilities were dormant.

Reality Rippers, Stages.

Almost half of all reality rippers are pupilless, it's a defining trait.
They often start off at vanishing and appearing again, you can't find them in your own universe no matter what.
They can teleport, but a more defying trait us that they call it warping.
They can teleport or summon items at will.
They can open portals.
They have a strange knowledge of the multiverse.

Often at teenage years the stages will finish.

Peacekeepers Beginnings.

Most are AIs, it is uncommon for one to be organic.
They used to be someone before something happened.
At a critical point(s), they were sent through time and space.
Then (A) They never become a true Peacekeeper because the following never happens.
(B) The following happens and they are a true Peacekeeper.

Seen as an actual person.
Given a name.
Has their own form.

True Peacekeepers can sense Reality Rippers and Vice Versa. There will be slight conflict between the two if they don't know what the other can do, but otherwise, they can form close bonds if one doesn't attack the other for a long period of time.

But if they are told of the threat one posed to the other, they will attack for one survivor.

(Fun Fact, if you screw with one Reality Ripper many more will come to that one's rescue. This never happens for Peacekeepers, they fight alone.)