What are the main differences in Giant's Toughroad and Revolt drop-bar bike series? I'm at a bit of a loss trying to decide what sort of a (Giant) bike I should be looking towards.
I used to have a Ribble Sportive 7005 from 2014 to 2017. I am now looking for something that would enable a better posture for a longer (50-150 km) ride on gravel, compact dirt, and tarmac.
Firstly, I'm looking at Giant because it's one of the few reputable companies that offers anything in my area that I'd feel comfortable going with—including one of the only ones that have at least a slightly relevant model for trying out.
I've been looking at the Giant's Revolt series, but the differences between the various options are not very well described by the company:

Toughroad SLR GX: &quot;When you’re unsure what lies ahead—smooth roads, gravel or dirt—and you relish the adventure of quiet backroads, this is the bike. With its lightweight aluminum frame, drop handlebars and rugged, high-volume tires, you’re ready for anything.&quot;
Revolt: &quot;Over half the world’s road are unpaved, offering ample opportunities for adventure on gravel, dirt and scenic byways. This lightweight aluminum all-rounder is the perfect way to explore roads you’ve always thought about but never ridden.&quot;
Revolt Advanced: &quot;Almost anything goes in gravel racing and riding. It’s a mixed-up challenge of speed, endurance and handling. This high-performance all-rounder does it all. It’s smooth, it’s efficient, and it’s your new best friend for pushing limits on roads, gravel and dirt.&quot;
Revolt Advanced Pro: &quot;Almost anything goes in gravel racing and riding. It’s a mixed-up challenge of speed, endurance and handling. This high-performance all-rounder does it all. It’s smooth, it’s efficient, and it’s your new best friend for pushing limits on roads, gravel and dirt.&quot;

I tried a comparison on the Giant site, but it wasn't particularly helpful except for highlighting that the Toughroad SLR GX should be worse in nearly every category. It helps to know that the technologies marketed below in the Giant comparison table relate to bike construction techniques.

Though the Toughroad SLR GX isn't marketed under the &quot;Gravel&quot; category, the description mentions relatively poor road conditions, and in the shop I went to, it was described as the &quot;lower level Revolt&quot;. Some other companies (Kona and Bianchi) don't make such a Gravel/Adventure distinction.
road.cc lists the Revolt 2020 model as one of its &quot;best gravel &amp; adventure bikes&quot; while bicycling.com goes out of its way to make clear that the Revolt Advanced is not a touring bike (which to my ears is synonymous to adventure/gravel). Instead, bicycling.com recommends a non-drop bar Toughroad SLR as a touring bike (and even one of its best)—which makes no sense to me. Meanwhile, Specialized Sequoia Elite which is described in this review as &quot;Gravel&quot; (but coming out worse than Giant's Revolt Advanced) is marketed as a &quot;touring rig&quot; by Specialized so there's some overlap here.

I've now also received the specifications for the Giant 2021 range:


How important are the differences between these Giant's adventure/gravel drop-bar series'? Are any of these more suitable by their configuration for specific usages (e.g., racing, touring, forest-riding, etc)?
Please note that answers which say &quot;Go out and try them all&quot; are extremely unhelpful in today's climate where a) many bike shops have been bought empty (e.g., Pelago everywhere), and b) some shops don't offer options for trying bikes in any case (e.g., Kona in my area). I was able to try a Giant Toughroad SLR GX for about 10 minutes, but that doesn't tell me how it would feel going for the 100th (nor the 20th...) kilometre.
I think you are confused about the frame 'technologies' that Giant offers. More boxes checked does not mean a better frame, the choices are mutually exclusive. 'Advanced Composite' means a carbon fiber composite (CFC) frame. 'ALUXX' means an aluminium alloy frame. CFC frames are generally held to be superior to alloy ones.

I'll give you that the 'SL' and SLR postfixes are confusing, intuitively they would appears to indicate a progressively higher grade of either CFC or alloy construction, but the lowest spec bike has the SLR tag. 

It's very obvious that the Revolt Advanced is the better bike, and the Toughroad the inferior. Generally the Toughroad series sits below the Revolt in Giant's range, with a bit of overlap.

The 'gravel', and 'adventure' adjectives don't mean much. Asking who are these bikes are for is a kind of meaningless question. What you should do is find stores that have the bikes you are interested in, sit on the bikes and do some test rides. Figure out which gives you the riding position, ride and handling you are looking for, then decide how much money you want to spend and which level in the range you want to get.