Everything is different. Other than styling, these two bikes have almost nothing in common.
Both are narrow, chopper-like cruisers, both are renamed models dating to the 1980s, and both have a reputation for being very durable. Both have a hydraulic clutch.
The S50 is 800ccs and water cooled, very light, agile, and quick as all get out. It had a rear drum brake. The S83 is a larger 1400cc air/ oil cooled motor, in a larger frame with longer forks. It is taller, longer, heavier. It has a higher top speed but is not as quick. It has a rear disk brake and larger & wider tires.