Nolvadex (Tamox. Citrate) and Clomid (Clomiphene Citrate) are BOTH Selective Estrogen Receptor Modulators (SERMs). They are not AIs as they don't inhibit the synthesis of aromatase enzymes which means you have a less likely chance of having testosterone convert into estrogen. SERMs bind to estrogen receptors which basically blocks estrogen from exerting its effects in your body.
A.I. -> Stops test from converting into estrogen.
SERM -> Prevents estrogen from binding to their receptors in your body.
Both are used during cycles where there is a high chance of aromatization (conversion to estrogen), but this is sometimes dependent on the individual's susceptibility to estrogen conversion. Generally, they are not used in the same instance (A.I. and post cycle therapy (pct) are used at separate times) and the reasoning behind this is that using an A.I. during post cycle therapy (pct) causes your estrogen levels to be pretty low, and adding in a SERM to prevent that low estrogen level to bind will potentially mess up your hormones. Not to mention that low E levels correlate to mood swings and dry and achy joints as well. Nolva does have AI-like properties (some studies have shown that Nolva has gyno reducing effects), but it's best to invest in an A.I. for that kind of stuff as they are much better at lowering aromatization.
Sorry I can't provide good medical articles, but there's a plethora of information on this matter in the stickies on the forum. Just go in there and read up on what is what and what they do.
