Do only speed bleeders have the hole near the bottom ?

Clean the non-threaded end very carefully (brake fluid is poisonous) and gently try to blow thru it. If you can, they are not speed bleeders...
Looks like normal bleed screws to me, just different styles.

Thanks; And I can blow air through 2 and cannot blow through the other 2

Speed bleeders have a little check ball/spring inside them. Normal bleeder screws just have the lower hole intersect the center hole with nothing inside them. All bleeders will have those holes in the bottom...that's how fluid get out when the screw is opened. Much like a tube nut on a hard brake line, the threads don't (shouldn't) seal anything, they just force the end of the screw into the seat in the bottom of the hose to create a seal. The tip of the screw doesn't need to be a point, it just needs to be smaller than the port diameter in the bottom of the bleeder of the bleeder hole (acts like a needle valve). The long screw is a front and the short screw is a rear.

Interesting …learned something new ie long vs short

Here’s a picture of 1

Click to view attachment

Coincidently, I just got a set of Speed Bleeders delivered today. Once I get these installed I will report results.

Are the bleeders the same for both fronts and rears ? And, what is the size designation for those ?

Threads are M7x1.0 on both front and rear.

I don't have the lengths handy right now but the fronts are longer than the rears...

Do front 911M use the same size ?

yes

Yes, the short ones.

Whts the reason the front calipers require a short bleeder ?

Speed bleeders are great. It allows you to use the motive pressure bleeder AND stomp the pedal while the system is under pressure.

On the 914 fronts, the long bleeder is required because the short one is tough to get a wrench on…pretty close to the bolt heads.

On the M front and 914 rear…plenty of room to get a wrench on the short bleeder. You can use the long ones everywhere, but manufacturers typically use the shortest that they can get away with…no sense having a bleeder hanging out in the wind.