For labour law, firms usually split between union and management. Union-side wouldn't quite be big law -- they tend to be structured as somewhat specialized boutiques. There's a bigger emphasis on fit and demonstrated interest in union-side firms than for big law in general. But the compensation and workplace environment is pretty similar. Management firms can be labour boutiques or might be part of a general, full service firm. I guess in-house is a thing for both, too.
For employment (i.e., employment standards, wrongful dismissal, etc), there's a lot of variety. As in, everything from legal clinics, to sole practitioners, to massive firms.
As employment is already well covered, I would comment that "Contract law" is too fundamental/broad to really be it's own practice area. Instead, most practice areas will rely heavily on a firm grasp of contracts.
You should also be aware that the boundaries between areas of law are not well defined and is often just a convenient way to digest the information. Is a case of sexual harassment at work employment law? Human Rights? Contracts? It probably implicates all of these areas and more.
Sorry to be off topic but this is really interesting. Where did you find that link? Is the original page linking to it still up?
I wouldn't expect them to have and even publish data from other schools.