Parts change all the time from all manufacturers and normally it is for very simple and benign reasons that they will change.
We can explain some changes but we are obviously not privy to all the reasons and, like owners of the products, we are not told if a part changes or, very rarely do we get told, it just happens. Most times though it's minor changes and it's a like-for-like swap but, on occasion it can be a little more dramatic and wherever possible we will advise of this in advance, so long as we know ourselves.
However, if we have advised that a part is the one currently being supplied and it's been checked then it will normally be the only option available.
Supplier Changes
Manufacturers don't make all the parts for all their machines themselves. Every single one buys in components from suppliers.
Parts such as seals, locks, capacitors, suspension, elements, fan motors and many, many more are simply bought in from third party suppliers to suit the specified need.
Suppliers can change things, say a material is not available or there is another issue and this necessitates a change to a component that they build then the part number will normally change along with the part.
Suppliers can also vanish, for many reasons, that forces changes to be made to ensure that machines can be repaired and serviced.
New Models
New models may well have extra functions added or removed and this can also mean a part change. In order to keep costs of the parts low it can be advantageous to just use the newer parts even if that means a small change.
This is a good thing for owners as it means your cost is kept low and you get the most up to date component.
Upgrades
It isn't common but parts can be upgraded from time to time.
This will often be due to some sort of issue raised in the field, even in a single country where for example the power supply might cause something to happen with a component, that means that the manufacturer chooses to upgrade the component to better cope.
Again, this is not a bad thing as it is a quality improvement that is happening.
Cosmetic Changes
We see this a lot on facias, fridge and freezer plastics, doors and suchlike where the cosmetic changes.
This can be a colour alteration or the like of removing the brand name and using a generic item. This is a very minor alteration and normally holds no effect whatsoever other than a slight change in appearance.