The short answer
Pressure washing uses water pressure as part of the clean; soft washing usually describes a lower-pressure approach with a treatment. Neither label tells you whether the proposed job is suitable for your home.
Ask for a specification, not a label
Two providers may use the same name for different processes. Ask what will be applied, how it will be applied, whether rinsing is involved and what the treatment is intended to remove. You should also know how long the expected result takes and whether a return visit is included. These questions are more useful than choosing the strongest equipment.
Start with the surface
Give the cleaner the paving, cladding or render product details if you have them. If the material is unknown, request identification and an assessment before the method is fixed. Existing cracks, loose joints, coatings and seals are part of that assessment. A method suitable for one material cannot be assumed suitable for every exterior surface.
Protect the surrounding area
Ask how the provider will manage runoff, nearby planting, doors and windows, pets and shared access. If a treatment is proposed, the provider should explain the product precautions relevant to the job. Do not mix household chemicals or improvise a dilution from an online cleaning recipe.
Agree the result and its limits
Compare the expected dry finish and any marks that may remain. A trial patch can help establish whether the result is acceptable before a larger area is treated. Ask whether the quote includes the trial and what the next step will be if the surface responds poorly.
Match the quote to the actual job
A patio wash, render treatment and roof assessment have different scopes. Use the corresponding service page to prepare the photographs and questions, then discuss the method with the provider through WhatsApp.