下手 と 苦手
They both means not good at something. My teacher mentioned the easy way to use it is 苦手 sounds more polite to use it when you talk about other people.
a similar distinction applies to 上手 and 得意 as well! 上手 is most appropriate for talking about others, while 得意 is more typical when talking about yourself, your family, or otherwise your in-group.
(side note: 苦手 can also be used to describe things you yourself don’t like or aren’t good at tolerating. for example, カフェインは苦手です = “i can’t handle caffeine”!)
Thanks for adding to this! I’m finding it useful too!