Import POS Orders lets you choose Automatic or your own import mapping for sales.
ShopifyPOS lets you makes sales in person using iPhone, iPad, etc.. In doing so, you may or may not identify customers or you may want to use a Default POS Customer.
Start with Automatic to get things working. Then, if needed, create you own Mapping by going to Connect toolbar, ShopifyPOS tool, and Save with a name you choose here.