imho, php is a little more "low level" than cold fusion... it feels like there's a lot of little specific functions in php that can be used together to do something you need... cold fusion on the other hand seems to have functions that automate a lot of repetitive stuff (like date formatting, array appending, etc)...
if you can do php tho, you can do cold fusion... not much of a jump there (i did php at my previous jop, now doing cold fusion... took less than a week to learn the syntax)
just my .02