AI Builder is similar offering like Microsoft Cognitive Services. Some of the main differences are the pricing model and intended use.
AI Builder is subscription based while Microsoft Cognitive Services are consumption based. For any new project, consumption based pricing is much better – at the beginning, while your service is not used a lot, you don’t need to pay a lot.
Here is sample price for Microsoft Cognitive Services / Custom Vision / Pricing
(as of July 2020)
From the table you can see that Free plan contains 5 000 training images and 10 000 transactions included. That is quite a lot. When you pass those numbers, it means that your service is probably well used, and then, good luck 🙂
AI Builder is meant to be used from Power Apps and Power Platform. It is quite nicely integrated, and is excellent for experimenting and learning.
Microsoft Cognitive Services is more generic. It exposes API for applications to use the models. Those API can be invoked from any platform, anywhere in the world. This generalization makes it a bit harder to integrate in Power Apps, but it gives it much broader usage.
In addition, Microsoft Cognitive Services allows you to download some of the models to the end device itself – so that it can be used without network connection or server expenses. But that is for some other story…