Needs Help With Ancient Greek Coin

This coin was given to me in 1970 (when I was 11 years old) for mowing a lawn. I have looked for months on the net to find out what it is. I found a similar one that sold for a great value.

The text reads (not my coin but similar one): BOIOTIA, Federal Coinage. Circa 287 BC. AR Tetradrachm (16.86 g, 11h). Attic standard. Laureate head of Poseidon right, wearing hair long at neck / Poseidon, holding dolphin in his right hand and trident in his left, seated left on throne with lion's legs at the front and decorated on its side with a Boiotian shield; behind, BOIWTWN downward. Head, Boeotia p. 83; Gulbenkian 920 = Jameson 2065 = Weber 3303 (same dies); De Luynes 1980. Good VF, even pearl grey cabinet tone, small area of flat strike on reverse. Extremely rare, a coin of paramount importance for any serious collector of Greek coins.

I show my coin and the coin I am comparing it to.
It is similar but the nose has a straighter profile. Does anyone have any idea? I would appreciate any advise! Thank you for all the help!
Tom



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