デジタル大辞泉 gives the following definition of 間投詞:
《interjection》「感動詞」に同じ。
It also gives the following definition of 感動詞 (emphasis added):
品詞の一。自立語で活用がなく、主語にも修飾語にもならず、他の文節とは比較的独立して用いられるもの。話し手の感動を表す「ああ」「おお」の類をはじめ、呼びかけを表す「おい」「もしもし」の類や、応答を表す「はい」「いいえ」の類も、文法的性質が同じなので、国文法ではこれに含まれる。間投詞。感嘆詞。
Both terms are identically glossed as "interjection" in all the J-E dictionaries I can find, and the definition for each in デジタル大辞泉 gives the other as a synonym.
This is the only case I'm aware of where there are multiple ways of referring to a part of speech (a la 動詞, 名詞, etc.), and so I cannot help but wonder if there is some technical sense in which these two terms differ.