in case the post was talking about 1 mining rig capable of mining both these cryptos then it was lying and it was a scam be cause you can not mine both of these with a same equipment!

bitcoin is mined by something called an ASIC (https://en.bitcoin.it/wiki/ASIC) while ethereum is mined with GPU. a rig for mining ETH is a set of graphic cards installed on a motherboard using risers. both GPU and motherboard is the same thing you can find in any computer hardware store (gaming GPU, and MB) with a good power supply. all of this is usually installed on top of a structure (i don't know if it has a name but something like a hollow case). you can even build one yourself if you know how.

images: https://www.google.com/search?q=eth+mining+rig