https://www.hltv.org/events
Anything that says "Major" on it is equivalent to a masters/champs. The next two largest tournaments are "IEM Katowice" and "IEM Cologne", you can think of those as 2nd in importance only behinds Majors just due to them being massive arenas, held every year since the game came out, and generally has the most prestige even if it's not the most money or a Major. Then there are tournaments where there isn't prestige, but money. This year that includes: PGL Events, Fissure 2025 Finals, Esports World Cup, Thunderpick World Championship. The rest are kinda like if Valorant's main competition was if we had International Minors, still a trophy and important but not a Major and not a ton of money. ESL Pro League is like Valorant's normal League Season just international and twice a year, and every other tournament is just for points to qualify for majors, whether large or small. This includes any BLAST or IEM events that are not the ones I've already listed.
tl;dr
Ranked in importance:
Anything that says "Major" = masters/champs, all top teams
IEM Katowice and IEM Cologne = not majors but massive arenas, held every year since release, most prestige only behind majors, most top teams
PGL Events, Fissure 2025 Finals, Esports World Cup, Thunderpick World Championship = money farming events, decent amount of top teams
Everything else in a big box on events page = Fun to watch, not very important but some top teams
Everything else = t3-t4 not recommended, level of play is low