STUMPERS XXI

Two six-letter words differ only by their last letter. In both words, inserting an O as the middle letter will give two completely different words. Can you determine the two six-letter words and the two new seven-letter words?

HINT:
The differing last letters of the six-letter words are R and T.

_ _ _ _ _ R
_ _ _ _ _ T

_ _ _ O _ _ R
_ _ _ O _ _ T

Answer:

The six-letter words are CORNER and CORNET.

With the O inserted as the middle letter, the words are

CORONER and CORONET