This is actually a great question that I wanted to address somewhere.
Punchline: What something looks like is a weak indicator of what trajectory it is following: glide or otherwise.
Reasoning: Look at this diagram:
View attachment 131817
Look how glide vehicles are shown above.
Yes, this is theoretical and for flat plates but roughly speaking it applies to warhead reentry too. The kind of trajectory that something follows can be abstracted to essentially the Lift to Drag Ratio (L/D), which varies with Mach Number. It is the L/D that decides what trajectory you will follow.
Another thing is that L/D becomes less and less shape dependent and more and more shockwave shape dependent as Mach number goes up. The shape of the shockwave depends on only a few design features of the vehicle and very strongly on its attitude (the angle it is making with the flow). Look how the glide vehicle area and the reentry vehicle (non glide) becomes closer at high Machs in the above diagram.
Final thing that I've hinted at is that L/D depends on the trajectory and the trajectory depends on the L/D. So this isn't a simple problem - you have to go back and forth.
All of this put together means this:
At reentry you are going at very high Mach numbers so you need to look the right hand-side of the above diagram.
You could launch a brick with an attitude control system towards the Earth and make it follow what you would call a glide trajectory.
You could also launch the X-15 and make its attitude be like so (square to the flow) that it acts like a brick falling through the atmosphere and burns up.
I hope that all of this helps clear your confusion.
@Quwa @arslank01