Er, what you exactly mean? Well first difference SMF is free and VB is not. and VB is much powerful and has many options if compared with SMF. Please specify exact point, where you want to compare both SMF and VB.
I installed both recently. They are really uncomparible. Oen is really a product and does its job almost perfectly (lots of features, great community and perfect presentation) and the other is free and very good for a free software compared to its alternatives (more secure). So simply: If you have money, buy vbulletin else use smf.
VB - more secure, more user friendly and easy to post.. More easy to gather information... More nice themes and hacks.. SMF - newer one, less secure ( my forum getting 3 spam members everyday).
SMF has been very secure for me though. And you can't just compare the security of these 2 forums. Lots of other factors are involved like the age of the forum, the theme, the amount of traffic,... Also, did you enable captcha? And to see the differences: http://www.forummatrix.org/compare/SMF+vBulletin But you just have to give them a try to see which one you like the most.
Most people hit up on the right points, anyway a quick overview: SMF = Free, decent amount of skins and mods., open source so it's easier to find the exploits. VB = NOT free! , more skins and mods. (you can get a rev. share mod for VB, and you can't do that with SMF yet (well unless you code your own), not open source, so the code is hidden, and you are protected against exploits more efficiently. So if you can't afford VB, stick with SMF, phpBB, or MyBB. Those are the best 3, but I'd narrow it down ot either MyBB or SMF. The gamer forum in my sig. runs myBB in case you want to know how a typical myBB forum looks like. As for skinning, never skinned a VB or SMF forum, but I did modify the MyBB skin (made only minor adjustments to the code though, most of the modifications consisted of graphics).
Main difference is one is free and another one is paid. Of course, you get better features with a paid product. DP used vbulletin. What do you think of vbulletin? Of course it is good!
That point about protection is absolute rubbish, whilst vB isn't open source (technically nor is SMF), it's code is not encrypted so exploits are just as easy to find. If you are suggesting that because you have to buy it to find exploits then that is debatable, you can easilly find a copy on pretty much every P2P network there is.
I wasn't aware of that, thanks for pointing it out Bendo. But either way since you pay for VB, their support team will probably release a exploit patch much quicker than SMF, or should anyways.
Well VB has a HTML driven template (even if it's in the admin panel and you have no external CSS to work on) and SMF has a php "seasoned" layout that gives you some nice parse errors when something doesn't seem OK. And since there are less php coders that HTML "aware" ones, I think it's clear which script is harder to skin
I kinda like skinning SMF forums though. Perhaps that's because I'm more a coder then a designer. But with the possibility to use the php you can do some nice stuff with it.