Tethered
The cable is fixed to the charger. At home you open the car, plug in, and you are done. The lead lives outside, so it wants a holster and a tidy coil. The fictional Lane 7 and Lane 7 Solar are tethered.
Untethered
The charger is a socket. You use your own cable, the same Type 2 lead (the plug shape most UK cars use) that you might already keep for public posts. The wall stays clearer. You handle a cable in the rain. Lane 22, the fictional 22 kW unit, is untethered.
Which to discuss
If you only charge at home, tethered is usually less fuss. If you already travel with a cable, a socket avoids a second lead. Say which you prefer on the quote. The sample price does not quietly swap the hardware. The survey confirms the unit.