BelalM

Exatcly right - the size and value factors are just a multifactor expression of the facts that typically, small firms have outperformed large firms (the "size" factor), and value firms have outperformed growth firms (the "value" factor).

All Fama and French did is express the spread of returns (small vs large and high book/market vs. low book/mkt) as risk premiums, and created a multifactor model to correct for these.