What is the difference between a hardtop and coupe 1965 GTO?

The main difference between a hardtop and a coupe 1965 GTO is the roofline. A hardtop has a fixed metal roof that is not removable, while a coupe has a shorter, sloping roofline and side windows that roll down. Additionally, a hardtop GTO typically has a pillarless design, meaning there is no B-pillar between the front and rear side windows, while a coupe GTO will have a B-pillar. Finally, hardtop GTOs usually have a more streamlined appearance than coupes, due to the lack of a B-pillar and the fixed roofline.