A vertical search engine is distinct from a general web search engine, in that it focuses on a specific segment of online content like videos on YouTube or Amazon for shopping. They are also called specialty or topical search engines.
Virtual assistants are bots that help you on websites and mobile phones using rudimentary AI technology.
Visibility is the term that describes how ‘visible’ your website is in the SERPs (search engine results pages) via organic ranking, paid ads, videos, news, images, etc.
This is the technology used to talk into your phone or laptop to get search results. There is marketing intent on voice searches that you should consider when doing your keyword research.