-what are different versions of sharepoint?: what are the features?

Sharepoint is a handy technology for portal usage. For such technology, many products are found in the market. Recently, I was a troubleshooter for Liferay portal. Your question is very vague as there are 3 types of people who develops or administrates or uses/integrates such product. You are confused because you started learning from wikipedia. I advice you to go through once more or twice else more and more times. Also go to one of the product. Check the pros and cons like searching or managing some widgets, processes(some call BPM) etc, then automatically u will know what level you were expecting initially.