External Hard Drive Formatting

This is from a previous post, but I accidentally checked that the second reply solved my question. Here it is:

I also have a new external hard drive, unused I mean, it is a seagate backup plus, exactly one terabyte.

But, it uses the Master Boot scheme, so this means I cannot partition it, and both the drives use the windows format, so I can't write to them.

My plan was to use an older windows computer to get the data from the old drive to the new one, then reformat the old one, but then I couldn't reformat the new one without losing the data from the old one. Unless I put the old data back onto the old one from the new one? I need both to be able to be able to read and write to mac, but both are windows and I have data on one. The unused one says it is windows format, so does this mean I cannot use it for mac at all?

Second Post:

I also have a new external hard drive, unused I mean, it is a seagate backup plus, exactly one terabyte.

But, it uses the Master Boot scheme, so this means I cannot partition it, and both the drives use the windows format, so I can't write to them.

My plan was to use an older windows computer to get the data from the old drive to the new one, then reformat the old one, but then I couldn't reformat the new one without losing the data from the old one. Unless I put the old data back onto the old one from the new one? I need both to be able to be able to read and write to mac, but both are windows and I have data on one. The unused one says it is windows format, so does this mean I cannot use it for mac at all?