which one is heavier 1.83 or 2.0

That depends, are the units the same.?  

Without the units neither have any weight so  they are equal in weight.

If you want an answer, we need more details.

1.83 tons is a lot heavier than 2.0 Kilograms, but 1.83 ounces is considerably less than 2.0 pounds.

Give us units to match the numbers! If it's the same unit, common sense ought to tell you that 1.83 < 2.0.