Most major PC manufacturers have a line of computers that they will label as "business" machines. What makes a notebook a business notebook? Special hardware? Software? Both of the above?
I've found that it's really a combination of both unique hardware and software features that make a computer a "business" machine. Compared to consumer products, business products may go through more use, misuse, and abuse (spill-resistant keyboards, shock-mounted hard drives, etc.). Business products also need to have the highest type of security protection (disk encryption, fingerprint readers, etc.). Business machines don't need all the "bloatware" that's commonly found on new PCs. Business computers are also often built to look less "flashy" than your average consumer-centric machines.
At the end of the day, you may still find all the features you need on a computer that's really meant for consumers. You can always install a new operating system on any machine. You can always increase some of the security features by using 3rd part software. You can remove the bloatware. However, it's not easy to add a fingerprint reader to a laptop, so if you need the highest level of data protection, then I suggest that you get a machine that includes a built-in fingerprint reader. Also, some mobile computers have special hard drive protection that is built into the BIOS. You can't add that with any 3rd party software.