200 KBps (uppercase B) is 200 Kilo BYTES per second.
There are 8 bits in a byte, so:
2 Mbps is about 0.250 MBps, or 250KBps
200 KBps is about 1,600 Kbps, or 1.6 Mbps.
Why you're not getting closer to the full 250KBps when downloading from Steam may be partly from the slight overhead involved in normal data transfer, and partly that your ISP might be providing "up to" 2 Mbps, or just isn't giving you full speed all the time.
My service is 100Mbps (about 12.5MBps), and I get around that, maybe slightly less, when downloading from Steam.