What is the difference between the D-Wave systems and the newly-born IBM Q System One?
When referring to the commercial quantum computers of both parties, it is that both are based on a different quantum principles.
The D-Wave machine works via quantum annealing and is suited for optimization problems. The machine by IBM is a gate-based quantum computer, similar to how digital computers work at the elementary level.
As the two quantum paradigms differ, it is also hard to compare them based on for instance the number of qubits (~2,000 vs. 20). The details of both machines can easily be found online.