is the apple watch series 1 and the first generation the same thing??

Hi

No, they are not the same thing.

Apple Watch (1st generation) refers to the original range of Apple Watch models, released in 2015.

Series 1 (and Series 2) models were released in 2016.

Apple offers the following resource for identifying Apple Watch models:

Identify your Apple Watch - Apple Support

To check your Apple Watch model - along with its service and support coverage - you can also enter the serial number here:

• Check Your Service and Support Coverage - Apple Support
• Find the serial number for your Apple Watch - Apple Support

The technical specifications can be compared here:

• Apple Watch (1st generation) - Technical Specifications
• Apple Watch Series 1 - Technical Specifications

The original  Watch and the  Watch Series 1 are two different animals. There isn't much difference, but they are different.

The original was available in Stainless Steel. The Series 1 is not.

From wikipedia:

As of October 2017, two generations and three series of Apple Watch have been released. The series in bold are the current generation of the device:

• Apple Watch (2015–2016)
• Apple Watch Series 1 (2016–present)
• Apple Watch Series 2 (2016–2017)
• Apple Watch Series 3 (2017–present)

Apple Watch Series 2 models are divided into four "collections": Apple Watch, Apple Watch Nike+, Apple Watch Hermès and Apple Watch Edition. They are differentiated by combinations of cases, bands, and exclusive watch faces; Apple Watch comes with either aluminum or stainless steel cases, and various watch bands; Apple Watch Nike+ uses aluminum cases and special variants of sport band; Apple Watch Hermès uses stainless steel cases and Hermès watch bands; and Apple Watch Edition comes with ceramic cases (the original generation Apple Watch Edition used 18-karat gold).^[67]

Apple Watch Series 1 models are only available with aluminum cases and sport bands.^[68]

Each model comes in a 38- or 42-millimeter body, with the 42 mm size having a slightly larger screen and battery.^[5] Each model has various color and band options. Featured Apple-made bands include colored Sport bands, Woven Nylon Band, Classic Buckle, Modern Buckle, Leather Loop, Milanese Loop, and a Link Bracelet.^[5]