Is there a technical difference between decryption and deciphering?
There's no actual technical difference, but it's sometimes used in different contexts.
Decryption: Used when talking about reversing an encryption of any type and when you know for sure that a message has been encrypted.
Deciphering: Used when (mostly) turning a ciphertext back to the plaintext, i.e. when a sentence has been encrypted with some sort of cipher like for example Caesar or Vigenère. It's also appropriate to use this term if people assume that a message has been encrypted or obfuscated.