Its not that one type of radio will receive better than the other, it really depends mostly on the antenna. Theoretically, with the same antenna, they should be pretty much identical in terms of reception. However, if you compare a handheld unit with a stock "rubber duckie" antenna and compare it to a mobile unit with a mag mount on your car or a discone outside or even in your attic, there will be no contest --- the mobile will win every time.
I'm not seeing much difference running my Uniden 346xt along side my BCT15X on similar antennas. They both track and receive almost identical. My 15x has a bigger screen, more audio and a bit easier to move around with the front knobs, but other than that they are the same.