Supernetting is the concatenation of networks, that is, changing the configuration of the devices found in two neighboring subents so that the two sets of devices are no longer on two different subnets but on one subnet, the supernet of the two. So devices in such a network will change their subnet masks from /28 to /27 and any other default gateway addresses that may need changing as well.
On the contrary, summarization is the representation of multiple networks with a single statement. If you have two networks such as the ones you mentioned in your post, the summarization of the two will be: 192.168.1.0/27. This can be used in a Routing Table to represent these two networks with a single routing table entry.