Can I ask question about comparison? For example, if I wanted to ask a question about comparison of Star Wars, Star Trek, Halo and Mass Effect technology tier levels.
Yes (but probably no).
The very short answer is that trying to compare two different fictional universes is always going to be tricky. Over the years SE has tried to grapple with the subject of "Gorilla Vs. Shark" type questions, where you're basically comparing two dissimilar worlds. If you want to know...
"Which is the most advanced technologically, Star Wars or Star Trek?"
... for example, you're going to be on very shaky ground. Not only is this definitely a G vs. S question but it also borders very heavily on being 'unclear what you're asking' and 'opinion-based', all of which are considered valid close reasons.
That being said
If you're wanting to compare items that have a defined feature, it's possible to ask them. For example ...
"Which ship can go faster, the Millennium Falcon or the USS Enterprise?"
... would be perfectly acceptable. We know the top speed of both and can compare their movement directly with objects (galaxies, in this case) that have known dimensions.
So what should I do to avoid getting my question closed?
You've got a couple of choices. My personal suggestion would be to write the question out in notepad, precis it and post it into chat. There are usually people around (including higher-rep users with a strong knowledge of the site's policies) who'll be happy to offer advice on how to post without falling foul. You might also try posting a Meta question on the subject ("If I asked "X" would it be closed?"). You'll also get good advice but probably less interactivity.
As an addendum to the well-received "Yes (but probably no)", and in light of the back-and-forth on this question:
And its related meta:
I think we should make it clear that if we are doing direct comparisons of quantifiable properties, such as speed, weight, force, etc., and the question would thus be on-topic, then it should be done under the assumption that if the universes are using the same units of measurement as one another (or, rather, as we use in reality), that they can be considered equal.
That is to say, we don't need to question whether or not the fictional universes are somehow fundamentally different on some quantum level, or using weird amounts despite being portrayed to us, the readers and viewers, using our language.
Absent any contrary information explicitly given in the works, we should assume that 1 second, 1 newton, 1 gram, 1 lightyear, etc. etc. are equal between the universes being compared and our own.