The deep phonological awareness skills are called phonemic awareness skills because they pertain to individual sounds that build words, i.e. phonemes. This is the most detailed level of word structure that is relevant to reading and spelling.
Phonological awareness training can be accomplished without any reference to letters or written words at all, and most programs begin such training by using pictures, nursery rhymes, songs, and games of various sorts that involve only listening and speaking.
Most programs do introduce letters fairly early on, however. Thus many programs combine phonological awareness training with phonics or letter/sound correspondence training. It is still important to remember that pure phonological awareness does not involve knowledge of letters. Those acquiring literacy skills should be checked periodically to be sure that they have knowledge of word sounds and sound structure apart from knowledge of letters.