Difference between DVI & VGA cable monitor

Most of the time DVI looks better, but I have a monitor/computer setup where the VGA connection looks better. Not sure why.

I can't tell much of a difference. Maybe DVI looks 2% better, to put a number on it. Some people claim to see a huge difference.
 
To the human eye? Probably not for most people. Actually, people who claim to see a quality difference are probably just living a false belief, just like how some people believe there's a quality difference in short-length HDMI cables. If there's a quality difference, I wouldn't be able to tell and you probably wouldn't be able to also.
 
but with dvi you don't have to worry about the clock and phase settings while calibrating the monitor, and if those settings are even slightly off the picture looks like crap...
see here
http://www.lagom.nl/lcd-test/

edit just to ad, I wouldn't even think about using vga with over 19 inch screens...
 
When on normal monitor....There wont be any major differences....the only differemce i see is that VGA tends 2 produce slightly washed out colours and u could see Frame lags in HD videos.....