Amazon has the Apple Watch SE 40mm in several colors to choose from for $229 (regularly $279) and the 44mm model for $259 (regularly $309) with Free Shipping for a limited time.
Amazon has the new Apple Watch Series 7 41mm Aluminum in several colors for $329 (regularly $399) and the 45mm model in red for $359 (regularly $429) with Free Shipping for a limited time.
The Apple SE added a 30% larger Retina display compared to the Series 3 in a slightly larger case, 64-bit dual-core S5 processor, 2nd generation optical heart sensor, always-on altimeter, 50% louder than Series 3 speakers, 4x larger onboard storage compared to Series 3, Fall detection, compass, noise monitoring and Bluetooth 5.0.
The newer series 7 adds an always-On Retina display that is nearly 20% more screen area than Apple Watch SE and over 50% more screen area than Series 3. It has a new S7 with 64-bit dual-core processor that is up to 20% faster than SE, third-generation optical heart sensor, electrical heart sensor, and a blood oxygen sensor.