Will the .hex files be different if there is any change in the Keil version.
Indeed, the files will be different, probably significantly, changes within the code may be more subtle, you'd need to review listing files to understand the real scope of the changes.
To ensure the same output you'd need to control the tools, settings and all the libraries from which it composes the output.
Minor changes in size and placement of code will have significant and compounding effects in the .HEX and .BIN outputs.
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