The 1258US column comes from MSI's exact US store specification. The 616US column uses MSI's exact US datasheet. These are manufacturer specifications rather than results from testing the two laptops together.
What the differences establish
The 1258US lists more dedicated graphics memory and a higher panel refresh rate. Neither establishes a measured frame-rate lead. A 240 Hz display can refresh more frequently than a 120 Hz display, but a game still has to deliver the frames; resolution, settings and workload matter. The graphics names here explicitly describe laptop GPUs and should not be treated as the corresponding desktop cards.
The two storage entries total 4 TB as advertised in either configuration. MSI's US specification table explicitly assigns one 2 TB Gen5 drive and one 2 TB Gen4 drive to the 1258US. That does not establish identical physical SSD models, usable formatted capacity or a shared RAID arrangement between the laptops.
Memory and expansion need separate checks
Both configurations list 64 GB in two 32 GB modules. MSI's separate 1258US column lists two memory slots and a 128 GB maximum. That is a manufacturer support claim for this configuration; it does not validate a seller's replacement modules or establish the older 616US model's capacity limit. The installed 64 GB describes the factory memory, not an available free socket.
The 1258US store uses a literal “6400MHz” label for its installed memory and separately describes family support up to DDR5-6400 MT/s. Those statements do not establish the operating memory speed of a tested unit. Keep a module's specification, a platform maximum and a measured result separate.
The 400 W adapter is an adapter rating. The 99.9 Wh battery figure describes stored-energy capacity. Neither is a measured power draw or a battery-runtime result.
Check the 1258US listing carefully
MSI's 1258US page gives slightly different dimensions and weights in its labelled size summary and detailed table. Check the required clearance with MSI before relying on either entry for a close-fitting bag or enclosure. Do not turn that difference into a precise measured size.
For an upgrade listing, compare its exact model and changed components against the factory configuration above. The additional memory, SSD or service promise belongs to that seller's configuration and needs its own evidence.
Disclosure: This is a comparison of published manufacturer specifications. No hands-on performance, thermal, acoustic, battery-life or power measurements are claimed, and no current offer, stock status or seller warranty coverage is asserted.