Which is more difficult to understand: the origin of stars or planets?

Modern cosmogony explains the origin of stars quite clearly within the framework of the condensation theory. Apparently, this theory also applies to the formation of planets. However, it is very difficult to determine the specific mechanism of the formation of planets, since: a) the planetary system is a very stable structure that has “forgotten” its past; b) so far only one planetary system can be studied in detail; c) the main planet-forming molecules and atoms are more complex than the particles that make up the stars.