I think =1 is the Globex, electronic market and =2 is the open outcry market. Globex used to be active only at night, but now I believe it is also open side-by-side with the pit.
If you are trading crude oil, another symbol you might look at is QM, the mini crude contract. It has good volume and tight spreads, I believe.
Good trading,
Aaron Schindler
Schindler Trading