Green car worth it?

...thanks to all for further comments on 'the GreenCar'.. May i ask what is the difference between the 'Nozomi Shinkansen .. and the Sakura Shinkansen?'. Is one faster than the other?, .. a better service? I have just assumed that the 'Nozomi Shinkansen' was the best way to travel...hoping this 'Virus' will be over soon and can re-book for my return trip to Japan and to Hiroshima to visit friends there, hopeful again in November for 'aki koyo'. .. in advance, thank for any info.

The Nozomi stops at fewer stations than the Hikari and Kodama services, making it faster from Tokyo to Kyoto/Osaka. It is also the most frequent service. JR Passes cannot be used for Nozomi services, presumably to stop them being crowded by tourists.

Shinkansen lines get names to show where they are running and what type of train they are (well, in broad terms speaking). Read here all you never wanted to know about it:

https://www.japan-guide.com/e/e2018.html

https://www.japan-guide.com/e/e2018_tokaido.html

https://www.japan-guide.com/e/e2018_kyushu.html

It obviously doesnft help that JR is split in so many different companies. West, East, Central (?), Kyushu, Hokkaido (I think thatfs all, but might be wrong. )

what is the difference between the 'Nozomi Shinkansen .. and the Sakura Shinkansen?
The Sakura is a once per hour (usually) service operated by JRwest as an eight car configuration. Seating is 2+2 in ordinary reserved cars and are some of the most comfortable seats on the rail network. The Green "Car" is actually only 1/2 a car and has quite a cramped feel to it. However, it is the preferred train for holders of the Japan Rail Pass, so it gets crowded and reserved seats do sell-out.
Nozomi (like Hikari and Tokaido Kodama services) use 16-car N700 series trains. In regular cars the seating is 3+2 and in green 2+2. Nozomi usually make fewer stops, but all the trains run similar top speeds as there are many on the tracks at the same time.
One other interesting train on the Sanyo line are the 500 series trains (RailStar) that run an all stops service (Kodama) and that includes the once per day Hello Kitty service.