As for what CDers are challenged by and what TS girls are challenged by, Obviously there is things that we both have in common. Both are people who are born of a certain gender and have desires to look like act like and or be like the opposite gender. Where the road Y's off..... I am not going to say I think one has it harder than the other. It would all be perspective IMO. My perspective would be that in a way, it must be difficult for TS girls in that they are born of a gender that they simply do not match emotionally, at all. That must be very difficult to deal with, either by living through it, or through the process of transitioning. Even then, there will usually be plenty of people who know that what a person is now gender wise, they were once the opposite. They will still be "different" Although they will be able to live a life that is more suited to them.
However, in a sense, their struggle, however difficult may in some ways be more simple. Simple in that they are mentally different than what they were born as. And, as they go through life and deal with transitioning or just living more as the opposite sex they were born as, more people will take on an understanding that they are just not suited to the gender they were born as. Certainly there will still be many detractors, and those which will bring negativity or worse. But many who will accept this person as the gender which they are aligned with mentally.
As CDers go, while they still match their birth gender at least part of the time, their challenges may be more complex. Internally there may be more confusion. What am I? A TS knows. CDers it is a far grayer area for many. Many people in society and in a CDers inner circle may have a harder time dealing with a CDer. They are often married and are mostly the gender they were born as but.... and that is really it, but. It is easier for people in general to understand a person who is TS than a CDer who shares both feminine and masculine characteristics or desires. Men who dress as women, but don't really want to be women, and are still attracted to women. As the list above done by Michelle, which was well put together shows, there are many difficulties a CDer faces that TS girls who are out and living more as they are aligned do not.
I suppose in the end, being TS and not yet out, or having started any transition must be more difficult. They share the challenges of a CDer and face that challenge 24/7. A CDer can at any time for the most part be part of the normal crowd. Maybe a part time member of that crowd, but a member nonetheless. CDers can still live comfortably with their birth gender and associate themselves as their birth gender. So, who's to say what really is more difficult? Both do have the common bond of crossgender issues and that ultimately should be something that does not work against each other simply because of how far on the TG scale they fall.