SHA is a hash function and AES is an encryption standard. Given an input you can use SHA to produce an output which is very unlikely to be produced from any other input. Also, some information is lost while applying the function so even if you knew how to produce an input yielding the same output, that input wouldn't likely be the same one used in the first place.
On the other hand AES is meant to protect from disclosure to third parties any data sent between two parties sharing the same encryption key. This means that once you know the encryption key and the output (and the IV...) you can seamlessly get back to the original input.
Please notice that SHA doesn't require anything but an input to be applied, while AES requires at least 3 thins: what you're encrypting/decrypting, an encryption key and the initialization vector (IV).
