ssd drive full but hdd empty, what's the point

Your Apple Fusion drive is split.

Here is: How to fix a split Fusion Drive - Apple Support

This re-combines the SSD and the HDD into one (virtual) storage device.

Alternatively, you can install and switch to an external SSD, and boot from that, and move away from the Fusion drive. You might choose that external migration if there has been a hardware problem with the internal storage, or if you want the performance of an SSD. Fusion runs at SSD read speeds and SSD write speeds for what is on the SSD, but has to shuffle with the HDD what isn’t onto or off of the SSD.

soreeyes62 wrote:

I have heard of the fusion drive but no idea how to utilise.

Normally a Fusion Drive would appear to be one drive at Finder level. You would utilize it in much the same way that you would utilize gears on a car with an automatic transmission. The system would automatically distribute pieces of files between the SSD and HDD, shuffling things about as it saw fit.

If a Fusion Drive was intact, and everything could fit onto the SSD, the Mac might put everything onto the SSD. The SSD, being much faster than the HDD, is more desirable "real estate". The problem which your screenshot seems to indicate is not the use of the SSD to the near-exclusion of the HDD. I wouldn't consider that to be an issue, if your Fusion Drive was intact. The problem is that this seems to indicate that your Fusion Drive has split and now appears as two separate drives at the Finder level.

What is your question???????? It appears your Fusion Drive is split, that is what you need to address.

Follow the blue-text link for the steps to remediation.