If you want to update from one table data to another table you can easily inner join the table by the same id key field and set the table the alias to perform the update.

Let's say we have two tables named Products and Products_Copy. Basically, both tables have the same field information. We want to copy the column fields value of Products_Copy to the Products table. In this example, we want to copy the Name and Price value.

Here is the screenshot of both table designs including the table values.

What we want to do is to update the products with ID: 1 and 2. So it will have the updated product name and price.
We can do it easily by running the following TSQL query.

UPDATE P
SET P.Name = PC.Name,
	P.Price = PC.Price
FROM dbo.Products P
INNER JOIN dbo.Products_Copy PC
ON P.Id = PC.Id

Here is the final result after we run the above TSQL query.