There is a difference in my opinion between a tryhard and a player who is serious about winning.
Tryhards: Uses only the best stuff available(FAL, AN94, MSMC, PDW, MK48 with target finder, etc) Uses any means necessary for an advantage, no matter how cheap or unfair. Works hard for the victory; if someone on his team can't do a job, he will. May or may not talk trash before and after the game. Typically doesn't take losses well. Dashboards if he goes negative. Runs with a full party or squad 90%+ of the time. Camps, head glitches, etc.
The most notable thing about tryhards imo is their bad sportsmanship. They talk crap, act like they're better than most people, can't take a loss, and dashboard. A less negative, but possibly annoying thing, is that they typically are the people who have 10k+ kills with one guy, and less than 2k with other guns. Most tryhards are rude and difficult to get along with. Also, they play in an extremely annoying fashion, such as head glitching at the back of the map with a TF lmg.
Serious Players: Less addicted to one or two weapons. Use whatever they can to their advantage, but typically use less cheap tactics(spawn trapping, headglitching, etc) Puts the team and the victory first. Rarely talks crap, and usually doesn't talk crap first. Enjoys stiff competition. May or may not dashboard. May or may not have a party/squad. Typically plays with a balance of conservative, aggressive, and campy movements. Usually are better than tryhards except when the tryhard has the situation completely under his control.
Serious Players are typically the guys who will do what they can to win, but not to the point of being a jerk. Serious players are typically better sports at the game. They may still spawn trap, but they typically are over all not as rude to others. They also are usually specifically looking for good players to go up against, specifically because they enjoy a challenge. If a game is tough, they will adapt and fight harder as opposed to leaving. Usually.
macarena69 posted... "That's the point. I can do it, you can't stop me, I gain nothing from listening to you, come on me bro"