Can ya tell I know nothing about gardening??
Heirloom plants are traditional favorites and produce a similar crop generation after generation. Hybrids are commercial crosses between teo specific varieties. The seeds you get produce the desired variety (Early Girl, Celebrity, 1000 others), but the next generation often reverts to various characteristics of the original parents. That is about all I know about plant genetics. Clearly heirlooms came from other varieties, but I don’t know how someone keeps breeding them to get something stable.
nacl
Probably more than you wanted to know.