To continue on the discussion regarding what casual and hardcore mean... I'd say there are three tiers actually

"Casual", "hardcore" and
"lifer". (These are just my opinions; yours may vary.)
Casuals are the "I play this for fun, but I do other things for fun as well; one isn't really more important than the other, or at least not
much more important" category. Generally the kind of player who isn't too upset if s/he misses weekly things, like loot drops or challenge log entries or elite hunt bills... Because there's always next week.
Hardcore players are those who prioritize game time over other kinds of fun things, because they care really much about some aspect of the game. This doesn't have to be raiding or getting the latest and shiniest loot. It could also be collecting glamour equipment, levelling all classes to max, getting all the relic zetas, crafting really tricky crafts, fishing up that reluctant fish... Or anything else you might be focused on. They still do the things they need to do IRL, whether it be work, girlfriend/boyfriend/family time, household chores, but their main "fun" is playing the game.
And then there are the lifers, who (IMO) run the greatest risk of the game becoming an obsession. This is where you find the people who play an average of 10-12 hours or more per day. Whether it's because they're unemployed, skip sleep hours, don't care much for IRL socializing or something else, they cut down on "non-game" time as much as they possibly can.
Of course, all of these terms (in my eyes, again), do not say anything about the respective gamers' skill or 'eliteness'. A lifer can do high-end raiding four times a week, or just putter about for hours coming up with their next glamour outfits for all their jobs/classes... And a casual gamer might spend their limited time in the game reaching those high-end raids and focusing on doing only that.