Difference between Chemo and Tamoxifen

I think I understand (at a rudimentary level) how Tamoxifen works.  But what I am confused about is how it differs from chemotherapy. Is Tamoxifen systemic, like chemotherapy, or is its function limited to cancer cells located in breasts?  And, is it accurate to say that Tamoxifen stops cancer cells from growing, whereas chemo kills these cells?  Thanks again for your time.

[CCF-RN,MSN-rf]

Dear Rene01:  Tamoxifen and chemotherapy are both systemic.  That is, both circulate throughout the body.  Tamoxifen is a SERM (selective estrogen receptor modulator) drug. This means that in some organs (the breast) estrogen is blocked. In other organs, such as the uterus, estrogen levels are actually higher. It works by blocking estrogen in the breast so that estrogen receptor tumors cannot form or grow.  Chemotherapy is cytotoxic. That is, it kills cells.  It kills both cancer cells and other rapidly dividing cells, thus, the side effects.