There is no encryption in Bitcoin. It uses asymmetric cryptography for signatures, and it uses hashing. Encryption might be used by wallets, but that is not part of the consensus layer and therefore not part of Bitcoin.
Encryption is just a sub type of cryptography. In fact, signatures are a more common use of asymmetric cryptography than asymmetric encryption.
Isn't that...asymmetric encryption?
Hashing isn't really the same as encryption; hashes can't be decrypted.
Hashing isn't really the same thing... you're not "encrypting" data when you hash it, you're putting it through a one-way function that produces a consistent fixed-size output, such that if you provide the same input again, you get the same output.
Hashes aren't "reversible" in any reasonable sense of the word. Sure, you can keep guessing inputs until you produce one that has the same hash, but it's misleading to say that you're "decrypting" it. I'd instead say you're finding collisions.
To me, "decryption" implies that there's some secret you have which can take the hash and turn it back into its original input in constant or linear time. Using the word "decryption" to describe "finding a hash collision" isn't really correct.