GCM (Galois Counter Mode) is a mode of operation for symmetric key cryptographic block ciphers. GCM is ideal for protecting packets of data because it has low latency and a minimum operation overhead.
SIV (Synthetic Initialization Vector) is a block cipher mode that provides nonce-based authenticated encryption and deterministic, nonce-less key wrapping. SIV can replace any specification that uses the Advanced Encryption Standard (AES) Key Wrap Algorithm (RFC3394) or Triple-DES and RC2 Key Wrapping (RFC3217).
Gueron and Lindell have shown that GCM-SIV encryption takes only 0.92 cycles per byte on Broadwell, and 1.17 cycles per byte on Haswell. For short messages (up to 32 bytes), GCM-SIV is more efficient than GCM, making it preferable for key wrapping and processing of short messages.