Automated models work by matching your property to recorded attributes and recent sales. They know the year built, the recorded floor area, the lot and the last transfer registered through Information Services Corporation. They do not know that the kitchen was replaced, the basement was developed, the shingles are three years old or that the bathroom count changed, because nobody filed any of it.
Your City of Saskatoon assessment is a third number and it is not a market value either. Residential property is assessed using a percentage of value of 80 percent for taxation, on a cycle that lags the market. People routinely compare an assessment, an online estimate and an agent's opinion and assume the highest one is the truth. They are three different measurements of three different things.
The test is whether a number can show its work. Ask for the sold comparables, the dates, and the adjustments made for condition, lot and age, and see whether the reasoning holds. Joel Dyck's hand-reviewed valuation walks the property, records the improvements no model can see, and puts the comparables in front of you so you can judge them yourself.