I think that it means that thing #1 and thing $2 might appear to be just as difficult to untrained eyes while one would require very little work because of what's already available (libraries, data or whatever) and the other would be a very large task because most of the work hasn't been done yet (but of course a different engineer might be able to find more efficient ways to do things)
You comment reminds me of this: http://www.uh.edu/engines/epi879.htm