Is there any difference between the two "エ" in 「エフェクト」? The first is bigger and the latter seems smaller.
The smaller ェ is used in combination with フ, thus making フェ (fe).
Have a look at katakana combinations: http://nihongo.as.ua.edu/katakana.htm
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BTW, if anyone is wondering how to type ぇ or ェ instead of え or エ in an IME (wihout preceding characters); hit the x-key before pressing the e-key. – Will Aug 31 '14 at 7:48