If you want to know what Technical Writing is in detail, there are some excellent online resource that you should visit:
On this page, you will find attachments and files that provide details of the different kinds of reports, and types of writing students need to become aware of. These are probably handouts that students have received during a course I’ve taught. You are welcome to download and use if appropriate. My students are ESL students, so I always assume some kind of language support.