Lonely or Alone

I have always liked my own company, always managed to get things done when I have been alone, without worrying about being a perfect host and all that bollocks.
But of late I have found myself pulling back into myself, and although I have many friends (very few who actually visit me) I have been feeling lonely, or is it alone. To be honest I have never really known the difference between the two (or have I)
I hate this feeling, even when I am surrounded by people I still feel the same way.
I got a friend who says to me "You need a girlfriend dude, the last one you had was ten years ago". Maybe this is true but will it stop me from feeling this loneliness.
Why has it come over me, I never used to feel like this. I have always been a friendly enough chap, I have laughed with my friends, and cried with them. I have always been there for the few who I deem as family.

"Go out more, and meet new people"
Is this the answer, I have tried this and all I end up doing is drinking or standing alone at the bar, I engage people in conversation and still I end up on my own.
I have always been able to talk to people and I know I am not boring, not because of what I am or do but because everyone I meet always tells me "oh my god, you have such an interesting life".
So why do I feel like this why am I suddenly alone and feeling lonely?
Maybe there is no answer to the question, it's like "Why am I here" thousands of people will give you a thousand answers, doesn't mean that any of them will be right.

Maybe I am not lonely at all, maybe it's just that I am alone, I just wish I knew. Now if anyone reads this and wants to comment, please don't quote the dictionary at me. I already know what it says in there.

Maybe no one will comment, which is cool, I don't expect people to even read my ramblings. I set this blog thing up more for myself than others, just a way of getting a few thoughts down somewhere.

But it is an interesting point. Alone or lonely, which is which and when does being alone start to turn int loneliness.