Yes, MPEG @ 15 mbps looks better than "DVD" (DVD-Video 2.5 mbps to 6 mbps average) bitrate.
Even though DVD spec goes to 9.8 mbps, you almost never see that. Why? A 9.8 single-layer disc would hold less than 1 hour of content at CBR. A DL would hold about 1.5 hours. Make it VBR, and you can squeeze on a tad more, though not much.
But a BD-spec SD MPEG is 15 mbps CBR. No more, no less. So it's often about 3x as good. Multiple compression issues are gone.
There are plateaus for bitrate encoding. You see obvious different from 2.5 up to about 7, and it levels off. You don't really see improvement until it exceeds 12.5, and again it quickly plateaus after 15. The 15 encode looks the same as a 20-25 encode in many cases. It's not until you get to the 40+ are where you seen obvious improvements again.
It's all about how MPEG distributes the bits in the 8x8 encoding. Certain errors disappear at 7, 15, and 40 -- noting the 40 is a broadcast spec with a more complicated signal.
The exact issue change per encoder as well.