They need to have the same thread size, reach, heat range and some have variations that you need to match up.
Your Civic EX takes NGK plug number ZFR5J-11
Your CRX HF takes NGK plug number BCPR5E-11
http://www.ngksparkplugs.com/techinf...tnumberkey.pdf
Judging from that plug number decoding... they will not work well even if they did fit.