"Theoretically there's no difference between theory and in practice... but in practice there is"
DVI tends to be easier to get a good picture - VGA can produce exactly the same good picture if you spend some time setting it up.
>Monitors with DVI connections are LCDs
Not necessarily, there are a few CRTs with DVIs. Also, CRTs still have better colour reproduction and blacks than LCDs. I know a lot of graphics designers keep CRTs because they like the colour reproduction.