One of the main differences between perfect competition and monopolistic competition is:
Perfect competition refers to a market structure with many firms while monopolistic competition is a market structure with only one firm.
Both market structures require many firms, but there are product differences and brand names in monopolistic competition that do not exist in perfect competition.
Both market structures are identical. Economists just like to make things difficult.
There is easy entry for firms in a market with perfect competition but significant obstacles of entry for firms in a market with monopolistic competition.