What is the difference between subscribing to the annual business plan and the annual individual plan?
The difference is in what you can access. The business (Enterprise) plan provides exclusive access to courses and remote labs marked Enterprise or Pro.
Is there any difference in the number of computers that can use this account?
No, each account provides access to a single VM at a time.
And that reminds me, this license also grants access to a more powerful VM (8 vCPU + 15GB RAM vs. 2 vCPU + 4GB RAM).
You need two or more licenses for team access.