Before you compare every SKU
How Lenovo families and part numbers change the choice
The family name is the first useful filter. ThinkPad P1 and P16 are represented here by exact configurations with NVIDIA RTX Pro graphics. The T1g and T16g rows use GeForce graphics, and the Legion 9i is the separate 18-inch gaming model. Those labels do not decide which laptop fits your software. Check whether an application calls for a professional or GeForce GPU, then compare the processor, graphics, memory and storage attached to the full US part number.
Every documented ThinkPad on this page has two TB5 ports and one TB4 port. The Legion 9i has two TB5 ports. Once that layout is clear, similar-looking ThinkPads can still differ in ways that matter. The two P1 Gen 8 configurations share the same processor, RTX Pro 2000 graphics, 64GB of memory and 2TB SSD, but part 21Q80015US has an OLED display and 21Q80026US uses IPS. The part number keeps that display choice attached to the rest of the configuration.
Lenovo publishes family page codes, machine types and retail part numbers for different purposes. LEN101T0180 and machine types 21UE or 21UF confirm the P1 Gen 9 family, but none describes one complete laptop. A US part such as 21Q80026US or 83EY000XUS identifies a specific CPU, GPU, memory and storage combination. P1 Gen 9 and T1g Gen 9 therefore appear in the separate family section below instead of the retail comparison table.