What are the different trim levels on a Volvo? 
First you can look at the car rather than the power train, and here we divide the trim levels into: 
Momentum, R-Design and Inscription. Easy way to remember these 
Momentum is Premium – the price will be the best value for money 
R-Design is Sporty – Premium to Momentum priced, with a sporty look and drive 
Inscription will be Luxury – with a base car that has access to all the bells and whistles 

Momentum: In a word PREMIUM. On all models is not a base trim level by any means, it will deliver a premium design, top level technology and an array of standard equipment. This will give you a luxury SUV or sedan experience. What can you expect – Android Auto and Apple Carplay, no fee it is just there on all 2019 and models going forward. With the momentum trim you have the ability to get FWD, which saves on cost if not needed, and Leatherette instead of Leather which additional allows the cost to come down. 

R-design: In a nutshell this is SPORTY. The R actually stands for “Refined” – the R designates this to be the performance orientated trim level. The seats are more race car, built to hug you, the steering wheel has paddles so you can whip through the gears. Rather than a chrome surround this is changed to Black.  With an aggressive front line and a definite sporty image. R-Design is the racing car of the Volvo line up. You can further enhance your performance by adding Polestar software optimization. This will enhance your engines performance, delivering a sportier drive with more torque. No changes in Fuel Economy with this enhancement.  
In addition to this, we now have POLESTAR ENGINEERED (PERFORMANCE), a further level of driving normally denoted with Color coordinated Seat belts (typically a burnt yellow or Gold), bigger brakes (Brembo) with large color coordinated calibers, and and Ohlins shocks for superior driving and performance. These come with the same badge that you will see on the POLESTAR electric brand. This is available on the S60, the V60 and the XC60. 

Inscription: In a word LUXURY. Top of the top, maxed out with all the bells and whistles. For the Arizona customer – this trim level is important – you need it for air-conditioned seats. Sometime it is standard (XC90), or in the case of XC60 it needs Luxury seats added. AC seats are not available on the XC40. But in our hot Arizona weather conditions – Inscription gets you a cool seat in most cases. 

But if you a shopping for a Volvo, you need to consider not only the trim level, but also the Engine. So here is a bit of info – they all the same. All of them are 4 cylinder 2.0 L engines. They all start as a in line 4 Cylinder Turbocharged engine.  
With the XC40 you have the T4, but for the rest of the range XC60, XC90, S90, V90 V60 and S60, the engine choices are T5 to T6 or T8. Put simply in Horsepower terms. 

T4                 187hp 
T5                 250hp 
T6                 316hp  
T8                 400 HP – Dual engine Gas and Electric, (only on S60, S90, XC90, XC60) 
T8 Polestar Engineered 415hp  (only on XC60 S60 and V60 )