The Eurail map is totally incomplete : there are thousands more railways and stations!

In fact the vast majority of European trains are included, the coverage works by train companies and all the major ones are taking part in the Eurail system. Some notable exceptions :

• .italo high-speed trains in Italy (in competition with Trenitalia, the state-owned company)
• Ouigo low-cost high-speed and classic trains (regular trains run on the same lines)
• RER suburban trains network in Paris

Have a look at this guide and do not hesitate to come back with specific questions : https://www.seat61.com/interrail-and-eurail-reservations.htm

Sounds like you’re quite unfamiliar with train travel.

No worries, we’re happy to help here. Best is to read the gold standard website of train travel in Europe thoroughly: the man in seat 61: https://www.seat61.com/european-train-travel.htm There are many country specific pages. You can get practically anywhere. From the big cities, Paris, London, Berlin, Vienna, Warschau, to unknown places like Beernem, Franeker, Marktredwitz, or Génolhac and everything in between.

There are many sorts and types of trains:

Down is a ranking from fastest and less stop to slowest with more stops. The higher categories are often more comfortable, with a bar or dining car and better seats. You won’t find these on local services:

• High speed trains: TGV, Eurostar, ICE, Frecciarossa, AVE, Railjet, Snabbtoget… (very often with compulsory seat reservations, sometimes optional seat reservations)
• Long distance trains: Intercity (IC), Eurocity (EC), Regiontog,… (often with seat reservations, sometimes optional seat reservations)
• Regional trains: Regional Express (RE), Interregio (IR),.. (reservation often not possible, just hop on with a valid pass)
• Local trains: Regionalbahn (RB), Subarban (S-)trains, L-trains, Sprinters, Stoptrains, Train Express Regional (TER)… (reservation not possible, just hop on with a valid pass)
• Local traffic: city buses, trams, metro’s, RER, underground,… → NOT included in the pass (although they often look like trains). Can always be bought with very cheap tickets, only costs a couple of euro’s.

See it as hierarchical as a road network, with international motorways, national motorways, regional roads, local roads,… for every service, you have a different type of train, with differing levels of speed, comfort and service.

Just for info:

If you go on many planners for a journey from A to B you will see an option with each train suggested by the planner to show all stops. 

As a general observation High Speed and Intercity trains tend to have relatively few stops, and regional and local trains tend to stop at many intermediate stations.