A republic is a representative government that is constrained/guided by a charter or constitution. i.e. we can vote on representatives who can then create/change laws based on what the constitution allows. typically constitutions preserve personal freedoms and rights, protecting you from politicians who would like to have those rights revoked. aka, preventing an individual or government from becoming all powerful and ruling as they please regardless of individual rights and freedoms.
Direct democracy is not necessarily bound by constitutions or charters. The majority makes the rules in those situations. If the majority wants it and they have a chance to vote on it, it may become standing law regardless of how it might infringe on perceived personal rights and or freedoms. It can become very scary based on who is in power and what the mindset of the majority is when there isn't a constitution to act as a buffer.
Paragraph 2 is what you prefer