To me, it is only difference of the term. Islamic is considered to be relatively stricter based on Shariah principles and Muslim a lil relaxed as people visualize someone having a long beard and saying all the times when it comes to Islamic.
**Islam is Universal, while Muslims are all over the world with different cultures INFLUENCED by local non-Islamic traditions which crept into and become part of larger Muslim Culture. these acquired cultural traditions had nothing to do with Islamic culture.
It's so very common in India and Pakistan, where most of come from, the Hindu traditions have crept in and ingrained themselves in Muslim culture. they have nothing to do with Islam.**