A5:
As we show in our video, the A3 and A5 are very similar in design and specification. The A3 is a Micro-ATX case while the A5 is E-ATX. The only other noteworthy difference is on the back of the motherboard tray where the A3 has a single SSD mount and the A5 has two drive mounts.
A3:
Building a PC in the smaller A3 case requires some care as it is tight for space, however the open nature of the chassis makes the job fairly straightforward.