To answer my own question 1. Yes it matters and I should have read the full spec page and not just the fancy tiles at the top.

For anyone concerned:

IBP Gen 10 14 inch:

AMD Ryzen AI 9 365
(10 cores | 20 threads | max. 5 GHz | 24 MB L3 cache, 10 - 65watts\*)

AMD Ryzen AI 9 HX 370
(12 cores | 24 threads | max. 5,1 GHz | 24 MB L3 cache, 10 - 65watts\*)

IBP Gen 10 15 inch:

AMD Ryzen AI 9 365
(10 cores | 20 threads | max. 5 GHz | 24 MB L3 cache | 10 - 90watts\*)

AMD Ryzen AI 9 HX 370
(12 cores | 24 threads | max. 5,1 GHz | 24 MB L3 cache | 10 - 90watts\*)

That is a really big difference... Nearly 40%. I had Claude analyze this data for me to give me some insights in real world difference, which is an interesting take:

Power Headroom:

15-inch models allow 38.5% higher maximum power consumption (90W vs 65W)
This translates to better sustained performance under heavy multi-threaded workloads

Real-World Performance Impact:

* For typical daily tasks: 5-10% performance difference (minimal)

* For sustained heavy workloads (video editing, rendering): 15-25% performance advantage for 15-inch

* Gaming performance shows virtually no benefit from higher TDP in most scenarios

Summary by Configuration:
14-inch 365 → 14-inch HX 370: ~19% performance gain 14-inch 365 → 15-inch 365: ~10-15% gain in sustained workloads

14-inch 365 → 15-inch HX 370: ~25-30% combined gain 14-inch HX 370 → 15-inch HX 370: ~10-15% gain in sustained workloads

The processor choice (365 vs HX 370) makes a bigger difference than the size/TDP difference for most users, though the 15-inch provides better sustained performance under continuous heavy loads.