Angle of the Blade: Disposable Straight vs. Regular Straight

This may sound like a silly question, but does anyone else find that they can hold a disposable razor at a steeper angle than a regular straight? It may just be me, but it seems like I can get a smooth shave at a 30 degree angle with my disposable, and feel that a 15-20 degree is best for my vintage straight.

Anyone have any ideas on why this may be? The only thing I've thought of is that the edge of the disposable blade and the body of the razor are not on the same level of steepness. Sort of like this.

.l.

My edge is the lower case letter L, and my disposable straight's body are the periods.

Also, just letting everyone know my comparison. I'm using a disposable Charles Monsieur, and a Fram by Julius Mandler and Sohn.

Normally its the opposite, most notably with a feather, which only needs very little angle whatsoever.

I'm still new to honing straights, and I'm the first to admit I've not achieved perfection. But is this just simply an indication my razor isn't sharpt enough?