I think online friends are different to real-life friends in some ways. Not necessarily any worse or less committed, though naturally it's easier to get away from a Web friend who pisses you off.
I think if there are sexual motives, it might be easier to get bogged down in narcissistic needs, because those are easier to "fit" to somebody you can't directly observe. Some people can fall in "love" with a set of messages, even if they barely know what the other person looks like. I've been apparently loved by two "Web women" who really didn't know me that well, though they knew the warm, supportive side of me that I was so easily able to show them....in many ways it felt like an academic exercise, and reality eventually got in the way......I noticed things about one of them that I couldn't cope with, so I left. I met the other one eventually and discovered that we weren't really suited.......all kinds of things about her were wrong for me, and in hindsight there had been plenty of clues in her messages, but it was only when I could observe her directly that I noticed anything really wrong.
Scope for deception is greater - you can say anything you like and the other person has little chance of checking the truth of your words. You could invent a completely false persona. All they can see is your disembodied words.
Aspies might in theory do better online because they're often stronger with the written word than they are with realtime conversation. The social pressure if real-life socialising is much more of a challenge, so they might prefer doing things online. That could be disappointing if the correspondents ever meet, but if they've built up enough trust and regard for each other via the Web, then they might be able to relate the real-life person to the online experiences they've had with them.
I've been surprised by how near to real-life friendship a Web friendship can be. You can make promises. You can keep them or break them. So you can establish lines of trust. You can boost people's confidence or you can undermine it. You can be there for them or not. You can share your good and bad memories, your experiences, your hopes, dreams and fears. You can clarify or muddle their ideas. You can be charming or abusive. You can talk almost in realtime using instant messaging. You can share text, photos, music and videos. You can fall in and out of love. You can have cyber-sex. You can threaten an existing real-life relationship with your closeness, or you can respect it. You can flirt, tempt, tease, wind up, attack, defend. You can call them out or you can commend them. You can exchange phone numbers and postal addresses. You can send them gifts. And you can arrange to meet.
But there will always be something missing of course. You can't touch or smell them. Your ability to see and hear them is limited to telephones, video links, etc. You can't see any more of that person's life than they tell you about. You can't go anywhere together. You can't sit together or perform a physical task together. You may get the feeling that all you are doing is reading and writing on your own, though I think you're doing something much more social than that, if there's a real person at the other end who may read what you've said and answer you.
I think a lot of the difficulty in understanding online associations comes from the newness of the technology. It wasn't so long ago that all we had was snail mail. Many people are still struggling to come to terms with these new ways of communicating.
So I think there are differences between online and "real-life" friends, but they can be as real as you collectively want them to be. The choice of what you make of it is yours and theirs.