Please Explain The Different Models

Can somebody explain to me in, perhaps simple terms, the difference between these four different Gemini models and why/when I'd use each one???

https://preview.redd.it/vj9zlnspwmpe1.png?width=336&format=png&auto=webp&s=99534c6f3b10e62dca538ac1fd13ffc2036bfcde