No.
FireWire 800 = Mbps.
USB 3.0 = 4.8 Gbps = 600 MBps.
MB = megabyte.
Mb = megabit.
mB = megabyte. The use of a lower case m is incorrect.
mb = megabyte, but check your context. People usually use this form for bits because they don't want to capitalize things (the K, M, etc). Byte should be assumed when dealing with storage, and bit should be assumed when dealing with transport (buses, intertrons, and interconnects).
Well not really... in this case 4.8 Gbps = 4,800,000,000 bps. Damned marketing.
When you have a K, M, etc, you're talking about 1,000, 1,000,000, etc.
When you add a b or B (for bit or byte) you're talking about 1,024, 1,048,576, etc.
(1,024 is 2 to the power of 10, and is used in computer science because it plays nice in a binary system, where things like to be powers of 2.)
You may see some places talking about kibibytes or mibibytes or some other crap denoted by KiB or Kib or etc. This is a bullshit made up term that a bunch of non scientists invented to deal with the confusion among the masses. ("Why is my 300 GB hard drive only 279 GB?!")
Marketing people love to assume K, M, and G are the classical multiples of 1000, because when dealing with GB, you can advertise a 7.375% larger size than you actually have if you ignore the fact that 1024 is the magic number, not 1000.
This difference increases to nearly 10% when dealing with TB marketed sizes.
A drive marketed as being 1 TB in size really only has 931 GB. (931GB * ~1.1 = 1024GB, or 1TB)