Nuclear weapons are basically of gun-type, implosion-type, or fusion-type.
Gun-type bombs use explosives to smash a piece of fissile material into a larger piece of fissile material which leads to fission.
Implosion bombs are detonated by using high explosives to crush fissile material into itself which leads to fission.
Fusion bombs actually fuse lighter elements into heavier elements. This requires a lot of initialization energy. The energy required for fusion is obtained from detonating a small fission bomb (usually of implosion type) near elements that you want to fuse together.
From what I understand, all nuclear weapons have some sort of highly explosive material in them. However, I'm no expert.
thank you lol