If you believe that dead people have come back, you're religious.
...this might be controversial, but I'll argue that thinking you'll live again if you get chronically frozen requires as much faith as believing you'll live again in an afterlife.
There's not much evidence for either, so you're left squinting heavily at vague suggestive outlines, making your bets, then hoping and trusting it works out.
The difference is what you put that faith in, and why.
I would say they are similar, but there's a key difference there. One relies on believing in the ingenuity of humans and the improvement of technology, both of which have been observed. The other relies on believing in the word of people who came long before you, which has been observed to be less then stellar.
The fact of the matter is you literally have to choose between those 2 or giving up completely.
It actually requires more because there are numerous documented cases of the dead coming back to life within certain religious ontologies whereas cryonics is only a potential resurrection in the future with no precursor. Imagine a Christian doctrine of the Resurrection of the Dead without the Empty Tomb.
These are large differences. We can argue about inefficiencies, but people do recover from decades-long comas. People don't recover from being dead as a doornail.
Not yet they don't. Plus, depends on how you define dead. I know people who have recovered from being dead quite a few times.
Maybe we'll be able to reanimate people eventually; for the time being, people definitely do recover from comas.