Bonus depreciation is offered some years, and some years it isn't. Right now in 2022,it's been offered at 100%.
The most important difference is both new and used equipment qualify for the section 179 Deduction (as long as the used equipment is "new to you"), while Bonus Depreciation has only covered new equipment only until the most recent tax law passed. In a switch from recent years, the bonus depreciation now includes used equipment.

Bonus Depreciation is useful to very large businesses spending more than the Section 179 Spending Cap (Currently $2,700,00) on new capital equipment. Also, businesses with a net loss are still qualified to deduct some of the cost of new equipment and carry-forward the loss.

When applying these provisions, Section 179 is generally taken first, followed by Bonus Depreciation - unless the business had no taxable profit, because the unprofitable business is allowed to carry the loss forward to future years.

Groesbeck, Auto & Truck Sales, LLC.