I thought they both use the same Textreme layup now. Should be the same for the frame.

From the felt website for the IA FRD. Not sure if the 'UHC Ultimate' makes it any lighter or not:

Felt Integrated Aero Tri Disc UHC Ultimate + TeXtreme carbon fiber,

Edit - Felts website claims the frameset weights as :
IA Advanced - 4.04 kg
IA FRD - 3.8 kg

That would be for same size, and I believe they quote them for 54cm. Not sure why the OP wants to compare weights on two different sizes. But, difference looks to be around 200 grams for same size.

Thanks for the info.
The Felt I am considering is old model (2016). So the weight difference should be even more, I think.

I highly doubt that the weight difference come from paint scheme.

For example, 2020 IA model, advance grade frames are colourful.
They are more glossy, brighter and painted area is larger than FRD model. 80~100% of surface is painted with bright paint.

In comparison with Advance models, FRD is black. And 80% of it surface are is not covered with thick paint. 80% is bare carbon with matt finish.
Black painting and matt finish is much lighter than bright and glossy version for darker paint needs not that thick base layer. (<-> white paint needs thicker base)

I think, when you sand advance model paint off and cover them only with matt finish, the weight difference must be minute.I am 100% sure of it.

My advance IA disc framet has small stone chipping on its drive side and I found out that painted layer is quite thick.

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