In Call of duty Modern Warfare 2?

the yellow points you get when you kill someone or plant a bomb or anything of the sort...those give you XP or Experience Points. the more XP you gain..the more you LEVEL UP! as for the score..i think you get around 50 points to 100 points (depending what you do) for killing someone and etc. but these points dont pop up on your screen like XP do. in modernwarfare1, whatever popped up on ur screen was XP AND was added to your score. But now the system adds them differently.

I believe your score is just the points you get from base kills(excludes bonuses like long shot, match bonuses, challenges, etc.). It's what it shown on the scoreboard when you press the back button(or whatever depending on the system you are on).

Your XP comes from everything you do: kills, challenges, bonuses, etc.). So, to increase your actual score the only thing to do would be to get more kills.

use different weapons to get more points. tey both count towards uping your level