It is possible to edit the similar-to factor in a proposal's indented product configuration when a part is added to the quotation bill of material (BOM) which is "similar to" another part. The complexity or similar-to factor is entered in the BOM and is applied to the quantity of parts required to arrive at a cost which is therefore factored accordingly. This is very similar in concept to labor complexity factors however one subtle difference is that a complexity or similar-to factor in the quotation BOM is applied to the quantity not directly to the hours. As a result price-breaks or higher quantity discounts could get applied which would not have otherwise been applied to the labor hours.

Learning curves or realization factors are applied specifically to make-part  labor estimates to reflect the experience your company has making that part as well as the efficiency of the intended site or workers building the part, as compared to how the routing standards were derived. For example if the routing standards were derived based on what it takes to make 10 items in the US, and the proposal calls for 500 items to be delivered out of Germany then it is safe to assume that the time to manufacture one unit 500 times is less than the time for the first ten units (even ignoring set-up vs. processing time), because of the greater experience, learning and time to improve processes. Equally, your plant in Germany might be more or less efficient than your US plant.  These two aspects combine to make the learning curve or realization factor.

Complexity factor is not the same as learning curve factor, they represent two totally different concepts, even though they are both applied to make part labor hours estimates.