If you are referring to the 1TB Fusion Drive vs 256GB PCIe-based Flash Storage in the 2014 Mac mini?
The 1 Tb ATA drive will be slower to start and read and write files. The slower read/write can cause beachballs while the system has to wait for the read/write to complete. You have to judge how you use the system and if the delays are acceptable.
The 256 Gb Flash storage will be much faster read/write, but it is 1/4 the storage capacity. If you do not have a lot of files to store and will not have many more in the future, then the 256 Gb Flash storage would be a good option. If you do have more storage needs in the future that makes 256 Gb tight then connect an external USB3 drive.
A good compromise is the 1TB Fusion Drive. You would get a 128 Gb Flash storage fused with a 1 Tb ATA drive. You would have the Flash storage for fast OS operations and the spinner for storing larger media files.
The upgrade to 256 Gb Flash or 1TB Fusion storage cost the same.
If you get the option that has an ATA drive already installed (so that there is a connector) then you could replace the ATA drive with a SATA 3 SSD.And this is something I can't just swap out on my own?
Sorry, very new to Mac computers
If you get the option that has an ATA drive already installed (so that there is a connector) then you could replace the ATA drive with a SATA 3 SSD.
You can NOT replace the Apple PCIe-based Flash Storage because it is proprietary and there are no 3rd party manufacturers so the only option is hardware removed from another Mac.
See the below link to get an idea of what it takes and the tools needed to get to the 2014 Mac mini ATA hard drive:
https://www.ifixit.com/Guide/Mac+Mini+Late+2014+Hard+Drive+Replacement/32815
I have the mid tier model with the 1 T hard drive and I also have a crucial SSD in a Pluggable usb 3 external and for what I do there is not much difference between them. I mostly surf the net, bank ,write letters, youtube, I do not game. So unless you do something much more demanding there is not much difference. Start time for the HD is amount 40 seconds and with SSD it is about 15 seconds. I only shut down about once a month, so that does not come into play much
OP:
Exactly -which- "mid-tier" Mini do you have?
Is it the "late-2012" version (with 2 SATA drive bays)?
Or is it the "2014" version (with 1 SATA bay and a PCI-e blade drive slot)?