No interactions present.
I feel neither are mature brown-lipped snail. The bottom example, if mature, could be a white-lipped snail. I suspect both are sub-adult Cepaea, and therefore without lip of any colour (since the lip is only present in mature adults).
BMIG website: www.bmig.org.uk (centipedes, millipedes & woodlice)
BMIG Newsletters ~ www.bmig.org.uk/view/resource/bmig-newsletter
BMIG Bulletins ~ www.bmig.org.uk/view/resource/bmig-bulletin
Lat/Lng: 50.8109, -3.6633
OS grid ref: SS829025