They are all low in saturated fat and good sources of copper and manganese.
Properly cooked soybeans: This food is ... a good source of Dietary Fiber, Vitamin K, Iron, Magnesium, Phosphorus .. , and a very good source of Protein ..."
Notes: 100g provides - 6g fibre, 17g protein, 20 ug vitamin K, 175mg calcium, 5 mg iron.
Calcium-set firm tofu: This food is ... a good source of Phosphorus, ... and Selenium, and a very good source of Protein, Calcium..."
Notes: 100g provides - 2g fibre, 16g protein, no vitamin K, 860mg calcium, 3 mg iron.
Okara: "This food is low in ... a good source of Calcium, ... and Selenium..."
Notes: 100g provides - 4g fibre, 4g protein, (? no vitamin K), 100 mg calcium, 2 mg iron.
In terms of substitution and usage, my experience is that pureed soybeans have a consistency somewhat like cream cheese, and okara like wheatgerm. However, tofu and okara are a lot more trouble to make from scratch than is soybean puree. Tofu can of course be easily bought, and eaten as a meat substitute. But a lot of the nutrients are 'missing', gone to the okara - the only exception being the calcium from the set. Also, many uses of the softer tofus involve pureeing - and then there's soy protein powder, which when reconstituted is basically puree again.
Following Laurel's Kitchen, I made mushroom pate at the weekend, and enriched it with soybean puree where I might have used cream or cottage cheese in a non-vegan pate. It's very tasty! Today, I am going to use soybean puree in a smoothie, and in pizza dough. I will report back!