What's the difference between dejitaru and dijitaru?

What's the difference between dejitaru and dijitaru?

No difference.
Older generation may use デジタル as that is almost always how it was rendered pre-2000 (about).
Younger generation may prefer ディジタル since it sounds closer to the English word "digital".

Just variations of transliteration. There is no difference in meaning or usage, as Majestic-san wrote. The former one デジタル "dejitaru" is still more commonly used, I think.
Many variations like that exist in loanwords.
e.g.
December: ディッセンバー "dissenbā" / ディセンバー "disenbā"
tip: チップ "chippu" / ティップ "tippu"
diamond: ダイアモンド "daiamondo" / ダイヤモンド "daiyamondo"
foul: ファール "fāru" / ファウル "fauru"