The issue is seeing the different addresses in my wallet..
What do you mean? I didn't understand correctly. You don't have the address you think is yours in your Multibit wallet?
How are address and public key different?
Shorena already mention.
-snip-
A public key is a 256 bit number if compressed (or a 256 bit x coordinate and 256 bit y coordinate of a point if not compressed) calculated from the private key using ECDSA with the Secp256k1 curve.
A BTC address is a hash of a public key with a version number prepended, a checksum appended, and then Base58Check encoded.