Other than a faster processor and the introduction of Rose Gold color option, the Apple MacBook (Early 2016) also probably keeps up with the latest USB Power Delivery specifications given the Apple MacBook (Early 2015) was released when USB Type-C and USB Power Delivery technology was less mature.
It's important to note that non-Apple third party Type-C peripherals that worked with the Apple MacBook (Early 2015) may need need new firmware updates to work properly with the new Apple MacBook (Early 2016). Contact your peripheral maker if you see any issues so that you can make sure you have the latest firmware installed so that it works with the new MacBook as well.
We've already seen issues where some USB Type-C accessories under development work fine with the Apple MacBook (Early 2015) but without firmware updates, have interoperability issues with USB Power Delivery and DisplayPort using the new Apple MacBook (Early 2016). We'll report later how these may affect certain USB Type-C products with USB Power Delivery and DisplayPort that have already been released to the market.