Alpha particle and Subatomic particle

Alpha particle noun - A positively charged particle that is the nucleus of the helium atom; emitted from natural or radioactive isotopes.

Subatomic particle and alpha particle are semantically related. In some cases you can use "Subatomic particle" instead a noun phrase "Alpha particle".

Subatomic particle noun - A body having finite mass and internal structure but negligible dimensions.

Alpha particle and subatomic particle are semantically related. Sometimes you can replace phrase "Alpha particle" with "Subatomic particle", this phrases are similar.