Full Idea
The 'commutative' laws say the order in which you add or multiply two numbers makes no difference; ...the 'associative' laws declare that regrouping couldn't change a sum or product (e.g. a+(b+c)=(a+b)+c ).
Gist of Idea
'Commutative' laws say order makes no difference; 'associative' laws say groupings make no difference
Source
R Kaplan / E Kaplan (The Art of the Infinite [2003], 2 'Tablets')
Book Reference
Kaplan,R and Kaplan,E: 'The Art of the Infinite' [Penguin 2004], p.33
A Reaction
This seem utterly self-evident, but in more complex systems they can break down, so it is worth being conscious of them.