Email accounts Email providers and email addresses,

I have a new iPad (9th gen) and i'm trying to set up my email accounts. I have several ntlworld email addresses, some iCloud email addresses and a hotmail email address. That's 3 email providers so I presume that means I have 3 accounts.

Under Settings, Mail I can add an account and fill in the required information.

I've set up one  ntlworld email account and now I can either set up another in the same way OR I can go to the first one and  'Add another Email'. 

Using the  'Add another Email' option I can add an email address but I'm not propmpted for its password and I don't receive emails sent to it.

Using the 'Add account' option allows me  to set up the  email address with its password but that would mean I  end up with over a dozen accounts in total.

I'm confused. Within the Mail app what is the relationship between Email account, email address and Email provider?