It looks the same LOL.
I was running 1.5 and I can tell you that 1.5 was way faster then 1.4.
On a Mac there is no installer, we just drag the icon to our applications folder so you can have multiple versions if you name them different or keep them in different places.
Here read what the geeks have to say about it over on Slashdot.
http://slashdot.org/article.pl?sid=0...tid=154&tid=95