mortise and tenon
So many upholstery manufacturers are advertising that their frames now have mortise and tenon joinery. To really understand what they are actually referring to is first to really understand what a mortise and tenon joint is= I have provided that link to Wikipedia below.
Then contact any manufacturer and ask them to send you a photo of one of their mortise and tenon sofa or chair frames.
Then do a comparison of their photos to the images on Wikipedia. The difference will be startling, like comparing leather to vinyl.
Here is a link that might be useful: mortise and tenon info