The way that Merida uses to label their range of road bikes is quite straightforward, as I will explain here. Merida road bikes are generally classified into two main groups, Road Race and Road Comfort. Road Race consists of Scultura and Reacto, whereas Road Comfort has Ride and Ride Disc.
Scultura - Conventional road bike looks with an emphasis on a lightweight frame
Reacto - TT style of bike frame design with an emphasis on aerodynamics
Ride - Road bike with more relaxed geometry and extra damping from lower seat stay placement
Ride Disc - Basically the Ride with disc brakes
For each of these categories, the numbering signifies the type of frame material (aluminium or carbon), and also the grade of components used.
3 digit numbers (Eg. 400, 500) - Aluminium frame
4 digit numbers (Eg. 4000, 5000) - Carbon frame
One great thing I admire about Merida is that for their aluminium frames, they try to replicate the look of the carbon frame. For example, the aluminium Reacto 400 looks very similar to the carbon Reacto 4000 in terms of frame shape. Only upon closer examination is the aluminium welding visible.
The higher the number, the higher the grade of components used. For example, the Scultura 400 is an aluminium frame with Shimano 105 components, while the Scultura 5000 has a carbon frame with Ultegra components.
With this definition, it is easy to know roughly the type and grade of the Merida road bike just by looking at the model name and the model number.