Fujifilm cameras allow the photographer to pick film simulations, including Classic Chrome, Astia and Velvia. In the camera you pick a film simulation you want to shoot in, and the jpeg created will have this film simulation applied to it.
If you have a raw picture in the camera, it is possible to press "Q" to do some editing to it. This will create a new jpeg. It is possible to pick a different film simulation than originally shot in.
In Lightroom, it is also possible to pick a film simulation. All film simulations available in the camera are also available in Lightroom. For example, my X-T2 has the newer Classic Chrome available, while the older X-E1 does not. This seems to suggest the film simulations being 'backed' in the RAW.
This Fujifilm blog post seems to suggest that the film simulation should really be chosen when the photo gets made. That makes me wonder, is there any difference between the following:
I would expect no raw developer to exactly match the in-camera jpeg because it would defeat the purpose of developing the raw if all it did was produce results identical to the in-camera jpeg.
I use RawTherapee, and the colors can be close, but still slightly different from the in-camera results. Based on what I've read, different raw developers do differ from each other. Even Silkypix, which is the one that FujiFilm has chosen to use in their raw conversion software, doesn't quite match.
Based on experience, the jpeg produced by raw+jpeg is the same as those created by the in-camera raw developer when the same options are selected.
As far as jpeg-only is concerned, it is impossible to know whether it differs from the other options because there is no way to create the other images for comparison once the raw is discarded. However, I doubt that in-camera raw development differs from jpeg-only development because it would be more difficult, and pointless, to implement different processing algorithms for the two.