MrsT is planning on a tablet purchase, probably a Samsung for camper van trips etc. The idea being I have access to some film downloads and to use for photo storage(clear laptop)
So.
What do I need??
Looking at Seagate there is the choice between a “back up” or “expansion” unit? What’s the difference??

You may deduce I am no PC/tech wizard 😐

I’d get a usb hard drive for home back ups plus a big memory stick for films while away and backing up the camera. Any of the branded disks will do, Hitachi, WD, Seagate. Also bear in mind that one copy of something is not a back up so keep a copy on the laptop and/or look into cloud storage.

What’s the difference??

I’ve no idea but I’d guess Marketing.

I’m not sure I understand the question as to what you’d need beyond the tablet, TBH.

Storage capacity I guess as tablet would likely be limited in storage.

It might have expansion via a micro SD card or similar (though I find micro SD to be very unreliable. Had loads of them die terminally).

External drive of a USB type would work.

Or just keep everything in the cloud and download what you want at the time for the trip if there’s enough space, or if you have decent Internet access during the trip (guess not in a camper), download/stream as necessary.

Photo storage. Keep everything in the cloud and just load up stuff from phone/camera to tablet and let it sync to the cloud.

Sync photo’s and other storage to the could and a NAS in the house – access over your home network. Use the tablet storage and SD cards for the day to day stuff but not for long term IE clear when you get home.
Where are you getting your movies from? Netflix now do a download version, how much stuff you you want while travelling?

Buy a 200GB MicroSD card for the tablet, that should give you plenty of space for films etc.

For backing up from a camera, I would get a hard drive with a built in SD card reader. Then you can just plug in the memory card from your camera, and it will backup all of your photos.
eg WD My Passport Wireless should work, though it gets some poor reviews. Or Gnarbox, but it is rather expensive.

I’m very happy with my WD My passport thing – once I’d understood how it actually works!

It might have expansion via a micro SD card or similar (though I find micro SD to be very unreliable. Had loads of them die terminally).

Stop buying crap SDs from unreliable sources. I don’t think I’ve ever had a micro SD fail, ever. (I’ve had a full-size SD fail once, and that was back when they still came in Megabytes).

Cougar – Moderator 
Stop buying crap SDs from unreliable sources. I don’t think I’ve ever had a micro SD fail, ever. (I’ve had a full-size SD fail once, and that was back when they still came in Megabytes).

Top name SDs from big name companies, high street retailers (pc world/currys type of places, usually because I’m desperate and need it that day so pay a premium). Not fake crap from the likes of ebay/amazon marketplace etc.

Sandisk and Kingston in the main, some PNY, one was factory supplied Nokia (mini SD). I’m down to two working out of 8. That’s not counting the numerous Compact Flash I’ve had die. All Sandisk.

Just had another one nearly die in the phone. Phone crashed and then it wouldn’t load anything from the card. For a change though it could just about be read by a PC, but was tough going to recover. Partition table trashed. It’s showing signs that it’s not happy though so that card is on the way out.

Most I’ve had die terminally to the extent they are not recognised in any device or PC. Doesn’t even acknowledge that anything has been inserted.

It’s the (un)reliability of particular nand flash used in these cards.

Reading around it seems the likes of Kingston repackage micro SDs from other big names as they can’t afford to make them themselves at the price points they sell for. Kingston cards apparently are Sandisk/Toshiba nand chip based.

Apparently Sandisk/Toshiba and Samsung are the main nand suppliers. Not sure how many I’ve had with Samsung chips. Not tried a Samsung branded card but seen mixed reviews on their own site with many claiming poor reliability also.