Here is some info.

http://www.bikesportmichigan.com/bikes/difference.shtml
http://www.beginnertriathlete.com/...il.asp?articleid=938
http://www.fitwerx.com/...advsTriGeometry.html
http://www.performancetrainingsystems.com/...s_road_tri_bike.html

Here is my advice: keep all your newbie questions here in the Womens forum, you probably won't be as "well-received" in the Tri forum.

Do you want technical differences? Or just general info? Typically the differences are geometry/fit and components that are more race specific (aero bars, etc).

There was another thread recently about this... road vs. tri or something along these lines. I think it was a few days ago, so take a look-see!

Welcome to ST. Hope you stick around and post lots. It's always great to see more women contribute on here. Here's some random thoughts that come to mind:

• Buying a bike when you are first getting started is tough. Ask around your friends and family to see if anyone has a road bike that they aren't using. It would be great if you could get out and start riding without having to put out a lot of upfront cash. IMO, you can't really get a feel for what kind of bike you'll want/like until you start to ride on a regular basis. I rode a borrowed bike for my first 3 seasons.
• When you are ready to buy, you should also look into used bikes. You can get a whole lot of bike for less money when buying used. I bought my bike used from the bike shop that did my bike fit. They put on new brakes, cranks and pedals, so it felt and looked brand new to me, but it saved me about $800.
• Ask questions whenever you want, but also take a look at the ST Search feature. There is a huge amount of knowledge on the threads here and you can get many of your questions answered just by doing a search.
• Find a race as soon as you can and sign up for it. There's nothing like having a goal race in mind to get you through a winter of training.

Good luck and make sure you keep us updated on your marathon and your progress.