With road bikes, people make generalizations like "LeMond's have longer top tubes" or Brand Y has a more relaxed geometry, etc.

Are there any generalizations one can make about triathlon bikes? Is there any meaningfull difference between a Cervelo and a Guru?

Cervelo tri bikes are known to have a steeper seat angle. I don't know about Guru but Orbea bikes are the opposite, i.e. shallower and more relaxed. World Champ Craig Alexander rides Orbea and yet many other pros prefer more aggressive style like Cervelos. It depends on your riding style.

Of course, Cervelo's have the flip-able seat angle so it doesn't have to be as steep. It's there so you can switch from Tri to TT setup and back.

True, but Cervelo's two-position seatpost (75 & 78 degree) is steeper still than Orbea's (74 & 76 degree).

https://slowtwitch.com/cgi-bin/parse....%20and%20reach

This is the old stack and reach database at slow twitch but it gives you a general idea.

Here are my thoughts...

Compare bikes when they are optimized, Gerard of Cervelo admits a P3C can be ridden slack but is optimized to the 78 degree position.

Don't assume all bikes of a manufacturer will fit the same.

Don't assume listed sizes match up to each other.

Cervelo, Quintana Roo and Felt are in general all steeper, lower bikes.

Trek and Scott seem to be slack bikes that are low, so with either a forward position they would be steep/low or with a higher front end they'd be more relaxed. Kestrel's airfoil pro is the same way, Dan Empfiel lists it as high, but I would argue its a bike thats meant to have the saddle pushed forward.

Specialized is a more relaxed tri bike.

Quite honestly, a lot of companies geometries are all over the place like Cannondale.