Swiss Travel Pass and Eurail Pass - which one?

The RS website provides good basic information but you would be well advised to research Rail Passes on seat61.com . Generally rail passes aren't much of a saving compared to point to point tickets, but everyone is different. Be advised that rail passes often require you to pay for reservations, which cuts into any savings.

RailEurope is also a good source of information for rail passes: https://www.raileurope.com/en-us.

Nope not a no brainer.
The Eurail does not cover 100% the best part of Switzerland the lifts to the mountains in the Berner Oberland.
You might get 25% off that is about it. You don't say what you are planning to do in Switzerland so it is hard to say,

Thank you. We are planning to stay mostly in one place and use the train daily for return trips inside Switzerland. We recently did the same thing in the Netherlands and it worked very well. No slugging around of any luggage - it is always at the home base. We plan to do the scenic railways too, so I was under the impression that EuroRail covers some or the discount is comparable to on the Swiss Travel Pass. When you look here: https://www.ricksteves.com/europe/switzerland/guidebook-updates:

The Glacier Express and the Brig–Zermatt route are now fully covered by the Eurail Global Pass (but the Glacier Express still requires a paid seat reservation).
The Eurail Global Pass now grants a 50 percent discount on most lake boats, rather than covering the full fare (but boats on Lakes Thun and Brienz are fully covered by the Global Pass). Swiss Travel Passes still cover all lake boats in Switzerland.
With the Swiss Travel Pass, discounts on high-mountain lifts and trains are now only available on one of your flexipass travel days (whereas Eurail-brand passes still let you take advantage of discounted train and boat rides at any point within the pass's validity window). As always, any ride fully covered — rather than just discounted — by any kind of rail pass does require use of a travel day.

So, I found it confusing. It seems from this as if the Eurail pass covers almost more of the scenic routs?

The majority time the topic Eurail pass comes up on this forum is when someone has bought it and later realized they don't really understand how it works.

Where are you planning to go and do in Switzerland exactly? The answer to that question makes a difference.

"Steve's website" is only a link to Rail Europe and is no way from Rick Steve's. Rail Europe is merely a travel agent that sells Eurail Passes. You can buy the pass directly from Eurail.

It depends on where you are going. The Eurail Pass is not universally accepted by all the many railroad company's in Switzerland, many of which are actually private. The Swiss Travel Pass is universally accepted to any inhabited city, town, or village in Switzerland. For instance, if you are going to the Berner Oberland, going from Interlaken to Lauterbrunnen or Grindelwald, the Eurail Pass only gives you a 25% discount on tickets.

Thank you everyone. I see the Swiss Travel Pass is better for my purposes. I downloaded a Eurail Map and a Swiss Travel Card map and clearly see the Eurail Map has dotted lines (not fully covered) compared to solid lines on the Swiss Travel Card map. (I investigated the route from Interlaken to Lauterbrunnen). I will study the other scenic routes.

You mention that you plan to stay in just one place, but since you seem to have 15 days, it might make sense to split this between 2 locations. There is nowhere central enough to access the entire country as a day trip. Spiez can work well as a hub for the west (Berner Oberland, Zermatt, Montreux, Vevey...), where I would spend the majority of the time. To complete the Glacier Express route + see the Bernina railway, you could then spend a few days in Samedan or Pontresina. And you would need at least one final night close to your departing airport.

If I may jump in and ask...
We're planning to fly in to Rome early May, then take the train to Florence, Cinque Terre, Venice; then to Interlaken, Lucerne, Zurich. The trip is about 17 days.
Which type of pass should we buy? Eurail pass, Eurail pass One country and Swiss Pass 5 day?
Thank you

You need to price this out by researching cost of point to point tickets vs. rail passes. If you have a set itinerary, often you can save with advance purchase prices on point to point. The Swiss also have a 1/2 fare card that some people find beneficial. The real value of rail passes come in their flexibility. This value tends to become moot if you have set plans.