SRTM vs FSGlobal 2008

Would SRTM be comparable to FSGlobal 2008? That is, do they do the same thing?
I thought that they were both mesh add-ons but I read somewhere (can't find it now of course) that they are used together. That can't be right.
Has anyone tried them both? If so, which is better and what are the differences? I know one is free. Don't factor in the cost.
I thought that they were both mesh add-ons but I read somewhere (can't find it now of course) that they are used together. That can't be right.
Has anyone tried them both? If so, which is better and what are the differences? I know one is free. Don't factor in the cost.