bluejazzy

the first "optimal portfolio" you mention (line tangent to efficient frontier) is known as the market portfolio, and it's the optimal risky asset portfolio for ANY investor. (ie given all the different assets in the market, it's the best possible return for the risk.) that line is the CML.

the second "optimal portfolio" (tangency between CML and indifference curve) is the optimal portfolio for an INDIVIDUAL investor -- ie, their optimal combination of the market portfolio and the risk free asset. this is dependent on how risk averse they are (which is why you use indifference curves) -- someone who is more risk averse will have more invested in the risk free asset and less in the market portfolio, etc.

as far as I understand it, any line that tracks the risk/return of the risk free asset combined with a risky asset portfolio, is a CAL. the CML is a special case of the CAL, where the risky asset portfolio is the best possible one (ie, the market portfolio).