*Which of these two makes a better turnover (profit) for the casinos (land-based or online)?
If we talk about profits, gamblers will be much more able to gain big profits from casino games because there are multipliers or jackpots that can be obtained, for sports betting there are only odds and to get more profits have to use large capital.
Don't forget that sports betting has a parlay where the reward is multiplied depending on the number of games combined in the wager. Though it does not compete with lottery jackpots but it can go toe to toe with the slots max multipliers like the amount the person won in a 12-pick soccer parlay. His bet of $25 gave him a winning of $597,354.90 and his other winnings give his $50 wager of 52,693.50[1]
From my experience, it can also be said that the biggest wins and always larger amounts are when winning from casino games, but it is difficult and I admit that it is much easier to win from sports betting.
But of course everyone will have their own experiences and different points of view.[/quote]
Aside from national lottery, it was recorded that the biggest win in gambling is around $39,713,982.25 from his $100 wager. It was a Megabucks machine and the win is a record for the biggest Megabucks and slot machine win in history.[2]
*Which of them has the highest number of players?
It is kinda hard to say which one has more number of players since there is no data available to be compared but according to
https://www.casino.org/features/gambling-statistics/, in terms of popularity, Casino games take the no.1 spot among gambling activities.
But if @OP is asking about the number of player between a land-based casino or online casino it is obvious that an online casino has the higher number of players since offline casino space is limited, unlike the traffic an online casino can make.
[1]
https://globalnews.ca/news/10281366/12-team-soccer-parlay-wn-olg-kitchener[2]
https://www.tbnewswatch.com/sponsored-content/the-five-biggest-casino-winners-in-history-8046210