Atomic weapon and Thermonuclear bomb

Atomic weapon noun - A weapon of mass destruction whose explosive power derives from a nuclear reaction.

Thermonuclear bomb and atomic weapon are semantically related. In some cases you can replace phrase "Thermonuclear bomb" with "Atomic weapon", this phrases are similar.

Thermonuclear bomb noun - A nuclear weapon that releases atomic energy by union of light (hydrogen) nuclei at high temperatures to form helium.

Atomic weapon and thermonuclear bomb are semantically related. Sometimes you can use "Atomic weapon" instead a noun phrase "Thermonuclear bomb".