Is Apple watch as same as Kardia Band?

The Kardia Band is a replacement watch strap for the Apple Watch which provides heart monitoring, so it's an add-on to an existing watch. It costs $199 and requires a subscription at $9.99/month or $99/year.

No. They are not the same thing.

The Kardia Band is an accessory for the Apple watch. You need an Apple watch to use the Kardia band. You cannot use the Kardia band on its own.

Kardia Band for Apple Watch from AliveCor - Alivecor.com

Kardia Band allows you to take a EKG on older Apple Watch models that don't have that feature. Apple Watch Series 4 and newer have ECG functionality built-in, but Apple Watch Series 3 and older do not.