i believe it's called "interference type" vs "non-interference type."

for example the Mazda V6 2.5L is non-interference, but the I4 2.0L is interference. yung nga lang, according to a mazda master tech dun sa mazda yahoogroup, wala pa siyang nakitang I4 2.0L na nasira after napatid timing belt.. even though interference type siya..