Typically extraction involves getting a number of materials into solution, while separation involves separating them from each other. In the base metals production world, extraction might involve dissolving Ni-Cu-Co-Zn but leaving Al-Si-Fe behind. Separation would then not have to deal with Al-Si-Fe, but only separating the Ni-Cu-Co-Zn from each other - usually chemically. In the biological analysis world, extraction can mean dissolving several components from plant material, leaving cellulose and other material not of interest behind. Separation can be by a number of processes such as chromatography which allow determination of the amount of different species of interest.

Separation is a broad category term which covers many techniques to separate a desired analyte (components of a mixture) by distillation, filtration, evaporation, extraction, and chromatography. Extraction is the process of selectively removing a compound of interest from a mixture using a solvent (transference of compound(s) from a solid or liquid into a different solvent or phase.) For an extraction to be successful the compound must be more soluble in the solvent than in the mixture. Additionally, the solvent and mixture must be immiscible (not soluble in one another). There are three basic type of extractions: liquid-liquid, liquid-solid, and acid-base.

Think back to your general chemistry solubility or organics chemistry labs, in your general chemistry lab adding a liquid to a mixture of cations, and causing an insoluble salt to precipitate out of the mixture (liquid-solid). In the liquid-liquid extraction you search for a solute which is immiscible to the sample solvent and one which your analyte of interest is soluble. In organic lab, we would wash a mixture with water to remove water soluble products (starting materials, salts, reaction by-products) as the 1st step in the purification process to isolate analyte or molecule of interest, then we would proceed to use other separation techniques such creating conditions for crystal to grow or insolubility for the analyte to crash out of the mixture, then you would filter the mixture/crystals over filter paper, followed by drying it in the oven (evaporation), recording the dry weight, and then exploring other purification techniques such as distillation or washing your cake again to extract more soluble impurities with an organic solvent that your analyte is insoluble in.

I recommend reading https://books.google.com/books?id=z3BsDAAAQBAJ&printsec=frontcover&dq=Analytical+Separation+techniques+in+chemistry&hl=en&newbks=1&newbks_redir=1&sa=X&ved=2ahUKEwitu5-HvKf9AhX_kIkEHV9MAd84FBDoAXoECAkQAg It goes into the theory of extractions equilibriums and different separation techniques.

As Michael indicated, extraction is just one member of the general category of separations. The choice of separation process is informed by the differences between the molecules to be separated. For example, differences in volatility, physical size, charge, solubility, or affinity for a solid surface can be exploited using distillation, filtration, ion exchange, crystallization, or adsorption, respectively. Solid-liquid and liquid-liquid extraction leverage enhanced affinity of some molecule(s) for a liquid or second liquid phase. (A supercritical fluid may also be a consideration.) In Lyle's base metal extraction example, the separation is based on the higher affinity of Ni-Cu-Co-Zn for the solvent vs. Al-Si-Fe.

Sometimes, extraction and separation process are in the same part. Extraction is include in separation process, which meaning is to separate active compound (which, the actual meaning of extraction is process taken of the active compound out from a substance i.e. natural, leaves, flower, etc). Or, Extraction is followed by separation process, filtration.

However, the extraction mechanism like maceration, soxhletation, or microwave assisted extraction. For detailed information about that please read this article. Article Performance comparison of maceration method, soxhletation me...

Extraction: Obtained from a substance through solvent treatment, distillation, dehydration, or other methods. It should be the process of dissolving the extract in a solvent and then separating it, resulting in a mixture of solute and solvent.

Separation: Separating the components to be used in the mixture from other components is a preliminary purification process.

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