Multi-Head Latent attention is a redesigned attention mechanism that produces lower-dimensional KV-cache entries. Vector quantization can store KV-cache entries using a small number of bits per dimension while ensuring that the resulting attention scores don't change too much. So MLA needs to be part of the model from the beginning of training, whereas VQ can be retrofitted afterwards, and you could also combine the two.

MLA makes it so the keys and values used are a function of a smaller latent vector you cache instead of a key and a value for each token. KV cache quantization reduces the size of the values in the cache by using less bits to store each value. These two approaches operate on different parts of the process so they can be used in combination. For example, you can quantize the latents that are stored for MLA.