In Git, committing and pushing are separate. A commit records a change in your local repository; a push sends it to the server. You can accumulate commits locally for as long as you like.
Centralized systems, including Perforce and USourceControl, combine the two. When you commit, the change is recorded and uploaded in one operation. There is no local-only history.
This is deliberate rather than a simplification. On a binary-heavy project, local-only commits are a false sense of safety: the work is recorded but it is still on one machine, and one machine is exactly what fails. It also means teammates cannot see that a file has moved on, which undermines the locking model that keeps binary work from colliding.
The practical consequence is that in USourceControl, a successful commit means the work is safe on the server and visible to your team. There is no second step to forget before you close the laptop.