Wireless supports two modes of operation. The most common is INFRASTRUCTURE mode, where you typically have a centralized wireless access point (AP) and all wireless clients connect to that AP. IOW, clients never connect directly to each other, only INDIRECLTY as they are all directed through (in this example) the wireless router.
The other wireless mode is ADHOC, which means two wireless stations (say two wireless PCs) can communicate DIRECTLY. This is a peer-to-peer relationship. The downside is that unlike INFRASTRUCTURE mode, you can only be connected to ONE peer at a time. On the plus side, it's faster.
It's no different than using a wired connection where you have the option to use a switch (infrastructure) vs. a wired connection directly between two PCs (adhoc). The former allows MULTIPLE devices to communicate with each other, the latter strictly one device to one other device. The concepts are identical.