As nouns the difference between pills and poo
is that
pills is while
poo is (countable|colloquial|often|childish) excrement; faecal matter.
As verbs the difference between pills and poo
is that
pills is third person singular simple present of
to pill while
poo is (colloquial|often|childish) to defecate.
As an interjection poo is
(colloquial|euphemistic) expression of displeasure or failure; shit!.