The OCR API uses an older recognition model, supports only images, and executes synchronously, returning immediately with the detected text. But supports way more languages.
The Read API uses an updated recognition model, takes an image or PDF document as the input and extracts text asynchronously. But supports less languages.
If you are looking for more details you can click here
You can stay updated with the list of supported languages for Computer Vision APIs by clicking here
The pricing for OCR API atm is $1.50 per 1,000 transactions for 0-1M transactions, and it gets cheaper the more transactions you have.
The pricing for Read API atm is $2.50 per 1,000 transactions.
You can stay updated with the pricing for Computer Vision APIs by clicking here
The Microsoft Learn module that @Philipp Walther mentioned is also recommended!