No, that isn’t the case. A standard composite door is generally around 44mm in depth and has a foam filling. Quite a lightweight solution, it also has a GRP colour skin (better known as fibreglass).
On the other hand, a Solid Core composite door is about 48mm in depth and is made using laminated layers of timber, making it more robust and durable than a foam filled composite door. Its UPVC skin enables you to colour match with any door frame.
The two options vary in price, with one costing more than the other. To get the right door, just discuss it with an Amber advisor.