As hawk said, Standard aligns much worse than Advanced --
Band 5 cut-off (Adv) ~ 65-68/105 whereas,
band 5 cut-off (Std) ~ 76-80/105
However, they scale similarly (although Adv slightly better) meaning that an 85 in Std and in Adv will yield similar scaled aggregrate marks per two units. Both require large amounts of effort although I found the Standard modules much simpler than Advanced ones, so doing Standard isn't an excuse to put more effort into other subjects. Really, you need to be in the upper percentile of your cohort even if your school is highly ranked to just get a band 5 so I would advise you to choose Adv - if it doesn't work out you can always move to Std