Number of Connections

I am confused with number of connections that are being open for users. Gatling says it's messages and not threads but what I can observe that as I inject to start 100 users, netstat shows 100 new connections. How it is different from Jmeter then ?

Threads and connections are apples and oranges.

If you are using HTTP/1 with default behavior, you’ll have as many connections per remote as virtual users (assuming no concurrent resources fetching).
Threads are resources you need to do parallel processing. You can’t execute more threads at a given time than you have cores. Above this limit, you’ll be doing time slicing. The more threads, the more CPU burnt on context switching.
The difference in terms of core architecture between Gatling and JMeter is basically the number of threads you need to run virtual users. With JMeter, the ratio is 1 for 1 while with Gatling those are unrelated (you’d typically run run with ~40 threads on an 8 cores machine). The impact is less memory and CPU usage when you run thousands of virtual users.

How do we verify if it is HTTP 1 or 2 ?