What you quoted from AALZ is about Distribution and Control Equipment Terminations.
OK, good point.
So my AALZ excerpt above applies to the terminations at either end of a feeder, or at the supply end of a branch circuit, but not at a piece of utilization equipment on a branch circuit. Instead, the text excerpted below from AALZ applies to the termination at a piece of utilization equipment.
There is an interesting difference between the second paragraph of the AALZ text below and the previously excerpted text. Namely if you have say a 60A panelboard marked 75C and circuit breakers marked 60C/75C, you can use 75C or 90C rated conductors at the 75C Table 310.16 ampacity. Whereas for utilization equipment that requires a 60A circuit, it would need to be marked "75C, use #6 Cu conductors" (or similar wording) to permit the use of the 75C ampacity. In other cases you would need to use the 60C Table 310.16 ampacity for conductor sizing, and if the marking is just "75C", you need to use 75C insulation without using the 75C ampacity. [Edit: as noted in the first sentence of the paragraph, certain product categories may override this text; for example, IIRC UL 1995 on HVAC equipment specifies that termination are to be rated for use of 75C conductors at their 75C ampacity.]
So the AALZ text on Appliance and Utilization Equipment Terminations is stricter than the allowances of 110.14(C)(1)(a) on terminations.
Neither is about circuit ampacity.
OK, "circuit ampacity" is an imprecise term, and it is only used in the NEC in article 430.
So let me be more precise. When performing the ampacity check required by NEC 215.2(A)(1)(a) or 210.19(A)(1)(a), which involves ampacity without adjustment or correction, that is a "termination ampacity" check, and ampacity is determined via 110.14(C) / AALZ, and the ampacity is the unadjusted value from (almost always) Table 310.16 for the wire size connected to the termination, at the appropriate temperature of 60C or 75C, as determined by 110.14(C) and AALZ.
Cheers, Wayne
Appliance and Utilization Equipment Terminations
Except as noted in the general Guide Information for some product categories, terminals, unless marked otherwise, are for use only with copper wire. If aluminum or copper-clad aluminum wire can be used, marking to indicate this fact is provided. Such marking is required to be independent of any marking on terminal connectors, such as on a wiring diagram or other visible location. The marking may be in an abbreviated form, such as "AL-CU."
Except as noted in the general Guide Information for some product categories, the termination provisions are based on the use of 60°C insulated conductors in circuits rated 100 A or less, and the use of 75°C insulated conductors in higher rated circuits as specified in Table 310.15(B)(16) of the NEC. If the termination provisions on equipment are based on the use of other conductors, the equipment is either marked with both the size and temperature rating of the conductors to be used or with only the temperature rating of the conductors to be used. If the equipment is only marked for use with conductors having a higher (75 or 90°C) temperature rating (wire size not specified), the 60°C ampacities (for circuits rated 100 A or less) and 75°C ampacities (for circuits rated over 100 A) should be used to determine wire size. Conductors having a temperature rating higher than specified may be used, though not required, if the size of the conductors is determined on the basis of the 60°C ampacity (circuits rated 100 A or less) or 75°C ampacity (circuits rated over 100 A).
