High-tech and High tech

High-tech adjective - Resembling or making use of highly advanced technology or devices.

High tech and high-tech are semantically related In some cases you can use "High tech" instead the phrase "High-tech" as a noun or an adjective.

High tech noun - Highly advanced technological development (especially in electronics).

High-tech and high tech are semantically related in complicated topic. You can use "High-tech" instead an adjective phrase "High tech", if it concerns topics such as mechanics.