Hi @Anca Stan I'll make sure to include this in the Community walk through video I'm recording this week, thanks for raising.
Both have unlimited replies.
The difference is in the intent of the member who is posting. If a member is asking a question to which they want a specific answer, then it's best to post a "question". Posting as this type allows us to identify all open questions in the Community and make sure they get an answer. It also allows the poster to indicate if the answer worked, creating a better knowledge base for anyone with a similar question in the future.
If a member is sharing their thoughts or starting a discussion to get perspective from others without seeking one right answer, than it's best to post as a discussion.
#ApptioPlanning(ITP/ITFMF)