Arial Black
Adventurer
Comparing 3.5 and 5E spell descriptions is kind of pointless.
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from http://www.d20srd.org/srd/spells/invisibility.htm
The 5E version:
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The 3.5 version is a whole lot of dense game specific text you have to read through multiple times to understand with conditions, sub-conditions and exceptions.
I'll take a little ambiguity now and then with 5E for spell descriptions that are 3 sentences instead of 3 paragraphs and 1/8th the word count.
In my experience at the game table 3.5 had more rules disputes and a lot more page flipping/looking for specific arcane rules than 5E because no amount of clarification will answer every question. So I for one am glad they went with more relaxed language for 5E, the game is much more approachable. Even if we do have some people insisting that a dragon breathing fire on the party is not attacking.
Thanks for posting this. The trouble with playing lots of previous editions is that you mix up all your previous versions.

Even so, I remember a 3.5 Sage Advice which said that, due to the wording, if you have detect magic running then your invisibility pops if it catches an enemy (and I don't think that detecting magic matches the 'natural language' definition of 'attack') and the spell reads your mind to find out who is your friend and who is your enemy.
Meanwhile, the 5e version is clear and concise, as long as you believe that JC meant what he wrote! That is, both 'attack' and 'cast a spell' mean the rules definition of those terms.
If only JC himself would supply this specific answer...