Generally speaking, higher-end headphones are necessary for critical pro-audio work such as recording and mixing. That said, there are many mid-priced headphones that offer performance to meet the needs of musicians with home studios and modest budgets.
Earphones, also often called earbuds or in-ear headphones, are typically included with portable mp3 players. They’re often replaced by consumers with better quality models that provide improved sound and comfort.
Consumer-grade earbuds shouldn’t be confused with pro-quality in-ear headphones and earbuds designed for applications like monitoring live performances and other critical listening uses.