Macrium Free disk imaging

Ok, using a Macrium made boot USB I can create an image of my boot SSD (all partitions needed to boot Windows), to any other attached disk, this works perfectly.
My question is about using Macrium while in Windows, is the disk image made this way identical to the image made from using the USB boot disk?
I was under the impression that using boot disks was required because while Windows is running certain files are locked and open so an image made under these conditions would fail on restore.
Is this no longer the case?
Is a disk image made from within Windows now valid.
This question is not about file backups, it is about a full disk image made while Windows is running.

Ok, thankyou for that info, just read up on Macrium snapshot function, interesting read. I use both the in Windows and USB boot versions with intelligent copy on, tried both versions of backup and both don't include page file etc, the images are same size. I think from what I've been reading that Macrium also ignores a lot of other files this way to shrink the image size created.
Either way the snapshot function is what was most important to understand, so thanks for that.
As a side note, since removing my Optane module and the Intel RST drivers my backup speed to my internal SATA 3 mechanical drive has more than tripled, cant believe the amount of overhead from RST that slowed things down.
An image that used to take 16 minutes now takes 2 minutes (including integrity check).