Some characters look different handwritten and on the computer - how to learn the differences?
Ok, this is similar to another question about why certain people refer to 土豆 as peanuts and some as potato and some other people as something else.

Prior to the official process of simplification of characters there has already been different ways in which people were simplifying writing different characters, it didn't just happen overnight. So for certain characters and certain parts of characters there was already different ways of writing these.

And as per the language example above these traveled and certain simplifications were set in certain parts of the country so that there were regional differences. This in turn created sets of written characters used in different regions.

You can switch the character set your browser is using, but most pages now are served in Unicode.

I assume whatever encoding your browser has is not a standard Chinese font or Unicode. My Firefox browser detects the page as Unicode and it displays as follows:





UPDATE:

In answer to your question in the comments above as to which one is the right one for you to use?

Your best bet in answering a question like this is checking a dictionary. That way you can be sure you have the right one. The other resource you can use for this is wiktionary http://en.wiktionary.org/wiki/%E8%81%9A

You can also see variants of characters at this site, including yours here: http://chardb.iis.sinica.edu.tw/variants.jsp?cid=19626 but this doesn't provide information if or where this is being used.