ESPN pulls itself while the league is public. CBS and Yahoo are both locked behind logins with no open API, so those run off your own scraper feed or a pasted score line. The need math, the field and the tickets work the same on all three.
Legs track themselves off the live NFL feed — scores for moneylines and spreads, box score stats for props. Lines stay adjustable after you add them. The payout is whatever you type in — nothing here calculates odds for you.