If you look at the specs on your lap top it comes with both an i5 and an i7 variation, hard drives are 7,200 and 5,400 rpm, the GTX 860M card I was unable to spot on the comparison chart, but a GTX 970M is in tier six on TOMS. The maximum SSD is 250 gigs not enough for Trainz and the operating system in my opinion.
Your lap top maybe sufficient to run Trainz at the sliders settings you prefer to your satisfaction but a desktop is not limited in the same way as a laptop for example an AMD R9 295X2 or an nVidia GTX Titan Z class of GPUs are simply not available in a laptop. The mobile variations of the i7 chip are more expensive than the desktop versions. Basically you pay a price for having a laptop.
Cheerio John