This would be my best guess

In most cases, a mortgage company will also hold the lien to the asset that is used to secure a debt, but not always. Thus there is a difference between the creditor/mortgage company and the lien holder in the law, even though they are the same in most cases. In some cases, like say a bankruptcy estate, there might even be more than one panthaver. All the creditors that have a claim against the estate is then considered a panthaver and part of the panthaver pool, which are ranked internally against each other by priority. The panthaver with the lowest ranked priorities might not get paid at all, if the assets in the estate won't cover all the claims.

Mortgage banks service and originates mortgage loans.
While individual companies may call them selves a regional mortgage company, they are registered as banks and are members of the MBAA, link below.

*CAREFUL!*
Mortgage banks and mortgage brokers are different bodies, where a broker will sell a banks product for the bank, but does not originate the mortgage loan.

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Note added at 1 day14 hrs (2013-02-02 04:05:11 GMT)
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Please note, I did not write mortgagee for a reason; crappy keyboard.