An ordinary glass bottle cracks when boiling water is poured into it. But a borosil glass bottle does not ... why?

Normal?glass?is an insulator which means it is a poor conductor of heat. ... Borosil glasses have very low coefficients of thermal expansion which makes them resistant to thermal shock, more than any other common?glass. So, Borosil?glass does not crack?when hot liquid is?poured in it, but?normal?glass cracks.