I think it's a fine line, and it's all about how it is interpreted.
being friendly is sweet, being sweet is being caring, being caring can lead to romance, that's where flirtatious comes in!
Umm... I don't know. Sometimes you can be friendly and it can be misinterpreted as flirtatious.
There is a fine line...some people get them mixed up...tread lightly...
...however harmless , any innuendo pertaining to a sexual nature could be taken as flirting....
It is one thing to offer courtesy, help and compliments to a point. The line is crossed, in my opinion, when you are made to feel that someone is definitely hitting on you. Spending inordinate amounts of time with someone, arranging to see them outside the office, suggesting ways to someone of being able to be together or meet somewhere . . . all these sorts of actions cross the line.
Its different for others but I'd say if you talk about sex in anyway or interact sexually like a kiss or a slap on the butt its flirting. I'd say friendly would be things like hugging, shaking hands or giving gifts or things you would do for a friend.
I'd be wary though as some people don't like touch like me so things like hugs and unannounced pats on the back would freak me out but thats just me.
DTF vs I'm a professional with good work ethic
There's an extremely fine line... Friendly would respect personal space more than flirtatious. Friendly would be more relaxed and flirtatious would probably be a (tiny) bit more aggressive.
any conversation regarding sex is flirtatious. friendly is usually defined as making supportive observations about someone's achieivements, or their requests for help