Semantic technologies don't refer to a single technology, but rather to a side variety of tools and technologies that have to do with meaning. Some focus on structure, some on text, and some on intelligence. Understanding what sub-categories are out there can help you determine when to use each.
Semantic Web vs. Semantic Technologies—much of the content on this site is about the Semantic Web, but it's only one kind of semantic technology. This lesson outlines the others and how they relate to the Semantic Web.
Semantic Search and the Semantic Web—semantic search is an increasingly hot topic, and with the Google Knowledge Graph it has become intimately related to the Semantic Web.
NLP and the Semantic Web—natural language process and text analytic technologies can be powerfully combined with Semantic Web technologies.