And here's some of my notes from back when I also looked into this so you have it in a nutshell.
1. Desmethoxyangonin
Desmethoxyyangonin. Role in increasing the dopamine levels considered by scientists.
2. Dihydrokavain (DHK)
Associated with the "heavy" kavas. Appears to contribute significantly to the anxiolytic effects of kava.
3. Yangonin
Proven association with cannabinoid receptors.
4. Kavain
Associated with the "heady" kavas. More studies available than for other kavalactones, yet still it's unclear how it works. Proven anxiolytic, psychoactive and analgesic effects.
5. Dihydromethysticin (DHM)
Associated with "heavy" kavas, claimed to have long-lasting effects, proven analgesic, anticonvulsant, and anxiolytic effects, may cause issues related to benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide.
6. Methysticin
May cause issues related to benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide.
Typical chemotype description consists of six digits, representing the six major kavalactones. They're ordered by the contents: 321456 kava contains more yangonin than dihydrokavain, more dihydrokavain than desmethoxyangonin and so on. Digit 2 on the first position presumably indicates "heavy" kava. 46 as the start - very "heady".