Depending on your duties and responsibilities, it helps to understand even just a little bit, what type of connectivity needs are offered out there and which one would be best suited for your needs.
Personal Hotspot on iPhone: What You Need To Know
https://www.lifewire.com/personal-hotspot-iphone-what-you-need-2000766
What is MiFi?
In a nutshell, a MiFi device is your portable internet connection on the go. Your WiFi enabled device(s) ie. laptops, tablets, etc.. can camp onto the MiFi for internet connectivity.
https://whatis.techtarget.com/definition/MiFi
What is WiFi?
Something we all can't live without nowadays. There are free and paid types of WiFi. Most free WiFi's are "unsecured" and data speed results, connection uptime and reliability will vary depending on what is offered.
https://www.digitaltrends.com/computing/what-is-wi-fi/