How are the "highs" differant between "Crack cocaine" and "Crystal Meth"?

and i have heard "Crystal Meth" gives a high lasting 12 hours?

and crack only 20 minutes and contains and illgal substance?

why would anyone want "Crack" then?

and how is the high differant and similar in feeling?

has crystal meth use pretty much taken over the use of crack?

if so, when and how did it become known?

: http://alcoholdrugstreatment.info/how-are-the-highs-differant-between-crack-cocaine-and-crystal-meth