Deep cleaning takes longer and it can involve a fridge clean out, organizing cabinets, or something like dusting the shutters/fans... Just tell them what you want cleaned.
Regular is usually floors, counters, exteriors of appliances, bathroom surfaces. Deep cleaning could be moving furniture to clean underneath, walls, windows, interior of appliances - but you’d need a written list to know exactly what’s included
For me A regular clean is a surface clean. Benches, floors and tidying up. This includes wiping down the toilets, stovetops and vacuuming etc. A deep clean for me is all of the above, plus cleaning the showers, baths, deep cleaning the toilets, deep cleaning the sinks, dusting fans, cleaning the oven, cleaning light switches and door handles and what not.
Usually get a deep clean when you buy a new house and they properly wash the carpets and everything. It depends what you’re willing to pay for. I used to have a lady come for 3 hours every 2 weeks and she would focus on 2 rooms each time and clean them really good.
Near us a regular clean covers everything on display basically, they’ll hoover/dust/clean the outside of appliances etc. things that you would do on a daily clean of your own house. A deep clean usually covers inside cupboards, inside appliances/moving furniture to clean under it, sideboards/skirting boards etc
It depends on who is doing it. Some deep cleaners do things that others don’t so I would confirm prior to. Like for example there are deep cleaners that will move your stove and clean under it and who will clean the internal and external windows in your home , they’ll clean each blind / shutter individually and wipes down walls and base boards some do laundry and will make the beds, and will clean ceiling fixtures like lights and ceiling fans etc it just depends on each individual what they’re capable of and typically do and what you agree to. A regular cleaning is what it sounds like counter tops floors it’s very surface level and so typically they wouldn’t be going under anything or above and beyond if that makes sense
If it’s someone from an established company they typically have a comparison chart or a listing of what’s included in what service in their website/flyer. To my knowledge a regular clean wouldn’t include anything that has to do with bringing out a ladder or step stool or moving furniture (so maybe no walls, chandeliers, top of the fridge, pulling the whole couch out to vacuum and mop underneath)