Phonics is print-based and phonemics is speech-based. The two can be taught interchangeably. Phonics is teaching children to associate certain sounds with letters and letter combinations.
Though there are 26 letters, there are over 44 speech sounds–any many more spelling combinations to represent those sounds. For example, think of the long /i/ sound and the words: sky, like, tie, and might–all long /i/ words with different spelling patterns.
When teaching phonics, it is best to focus on one pattern at a time; this keeps the process less confusing.