DRV8825 has higher drive current capability (2.5A vs. A4988 of 2A). You won't use the 2.5A, but it means the DRV8825 will not overheat as quickly.
Also, the DRV8825 can drive in 1/32 steps, so you get twice the resolution. You'll need to wire it correctly for this, and you'll need to configure your firmware for this.