In Google, why do different results show when using www.abcexample.com vs. abcexample.com without the www?

[memetrader]

The answer is that http://www.domain.com is a different url to domain.com.

This is a domain 'mydomain.com'. This is a sub-domain 'www.mydomain.com' and so is this 'anything.mydomain.com'. A server could return completely different content for any of these urls so search engines have to treat them as separate individual urls.

In your case you need to 301 redirect the 'www' url to the 'non-www' url.

Also don't bother with Google's link command because they only show a sample of the links they know about. Use the Yahoo search command linkdomain:yourdomain.com -site:yourdomain.com

Yes it can make a difference from the SEO point of view because inbound links will count only towards the url they are pointing to. If you do a 301 redirect they will count towards the redirected url.

If you don't follow email me and I will expand.