をおいてほかに〜ない・ならでは: the difference
Meaning
No...but, Nothing else but, None other than
Past papers
Example
長年付き合ってきたパートナーに別れを切り出すのなら明日をおいて他にはない。
If you're going to tell a long-time partner you want to break up, tomorrow is the only time to do it.
ならではN1
Meaning
Unique to, Only, Impossible if not, Expected only of
Past papers
Tested 5 times in past papers
Example
このクリーミーで且つ重くない絶品のカルボナーラは地元の名店ならではだ。
Only a famous local restaurant could make a carbonara this creamy yet light.
How to tell them apart
「をおいてほかに～ない」: the ending must be negative (ない／いない); all others are ruled out and only this one fits.
「ならでは」: the ending is usually positive, about the special charm only N has: 「京都ならではの風景」.
「に限る」: your own opinion that 'this is the best': 「夏はビールに限る」.