The differences between the way I act online and face to face boils down to how much easier it is to open yourself when you're not constantly taking non-verbal cues about what other people think about what you're saying. Online I am seeking for certain threads and replying as I go, instead of being awkwardly being drag into an opinion disagreement before I notice.
I enjoy speaking my mind and I feel I have a friendlier attitude online because for some reason here I don't have to struggle with mental barriers about 'saying something wrong' or ruining the first impression. I also like giving my two cents in different topics and then years later dig them and realise how some of them have changed and how some beliefs I still hold the same way as back then.
With me, what I post is how I feel and what I think about things so don't you worry: I'm genuine when interacting online.