"Expensive topsoil" sounds a bit like an oxymoron to me!! LOL!
Seriously, bulk soil providers will label their stuff as they see fit. Really the only way you know what you are getting is to see it in person and judge its quality. Or trust your contractor to do so :-) In soil speak, sandy loam is usually a preferred mix, typically with equal parts of the three soil types - sand, silt and clay. And with a reasonable proportion of organic matter. But what I (and most others) consider sandy loam may not be the same as what your soil supplier does. Sandy loam should not be mainly sand.
And you want to avoid layering different soil types on top of each other. Without getting overly technical, that can create what is known as interface issues, which affects how water moves through the soil profile. That's why if you are preparing a seed bed for a new lawn, you should incorporate any added soil into the existing soil with a light tilling. It's a bit less of a concern in planting beds as the act of digging and planting usually provides sufficient incorporation.
Regardless of what they may be calling it, the soil you want to add should be light and fluffy with minimal rocks and adequate organic matter (usually compost). It can look slightly woody or barky (from the compost) and that's fine - that helps both with good drainage and moisture retention. And the soil should look rich and dark in color and with no obvious aroma other than an 'earthy' smell.
Too often, folks redoing or putting in new landscapes will skimp on the soil in favor of putting their money into the plants or other features. I think that is a huge mistake. The soil is the foundation of any garden and has an enormous bearing on how well your garden does and looks over time. Spend the money upfront on the best soil you can get for your purposes. You won't regret it.
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