2. Placental versus Adult Stimulation. HCG is a very powerful placental hormone for a developing fetus. It has a powerful stimulatory effect on multiple systems and is long-lasting in order to achieve a more stable and powerful effect. LH is actually an older molecule, present in all vertebrates, and is critical to adults.
3. Receptor Binding. Greater receptor binding affiinity to the LH receptor. 
4. Increased VEGF and Angiogenesis. HCG is considered safe and is used by thousands of men for the above purposes, but one potential concern, especially at higher dosages in older men, could be stimulation of VEGF and angiogenesis. Basically, these term refer to HCG’s miraculous powers to simulate vascularity and tissue growth in a growing and developing fetus. The problem is that VEGF in older individuals (and angiogenesis) is associated with the initiation and spread of cancer.  Cancers are the kings of unstoppable growth and feed off of VEGF. One study commented that “it is now believed that hCG is involved in placentation through activities such as maintaining angiogenesis of the uterine vasculature and promoting differentiation of cytotrophoblasts into syncytiotrophoblasts.” 
5. Different Gene Expression and Signaling. Both HCG and LH bind to the same receptor and thus produce similar physical effects, right? Interestingly enough, the answer is that, while both do bind to the receptor, they produce some very different downstream results. The reason for this appears to be that they initiate differing patterns of gene expression, i.e. trigger different proteins used metabolically by the body. This should actually not be a surprise when you consider that HCG and LH serve very different functions and purposes.
CONCLUSION: In my opinion, dosage with HCG is critical. This is a very powerful hormone, and research is ongoing as to exactly what effects it produces in adults. In men, HCG is particularly poorly understood outside of its effects on testosterone and fertility. And, as always, I will comment that, if a little is good, more will not always be better.