Bioidentical hormones are created in a compound pharmacy from wild yam and soy. The difference is that bioidenticals are compounded to be identical to what our bodies naturally produce. Bioidentical hormones have the same molecular structure as the hormones your own body creates.
Natural hormones refers to anything that you can plant, pick or pluck. They are often bought over the counter or on the internet are frequently not micronized or found in high enough dosages to be effective. Micronized means it is broken down in particles that can be absorbed through the skin. You could bathe in the hormones provided over the counter and your skin would still not absorb the needed amount of hormones.
Synthetic hormones are hormones manufactured and patented by pharmaceutical companies. These essentially are estrogen, progestins,and testosterone. Synthetic hormones have added side chains like methyl and acetate groups that are attached to the original molecule to create synthetic hormones.
Because pharmaceutical companies cannot patent anything that is bioidentical or natural (existing in nature). However, with that being said, there are several pharmaceutical companies now marketing bioidentical hormones. That may sound conflicting, but the pharmaceutical companies recognize that women want alternatives for hormone replacement therapy. The pharmaceutical companies have developed unique delivery systems like the patch and a new form of gel or capsule that has previously not been developed and they patent the actual delivery system (i.e. the patch is actually patented not the hormone).