they're not the same thing though.
Essentially 3 marking devices
SMB's, you tow these, dive flags, etc. but can also be safety sausages that are towed throughout the duration of the dive.
DSMB's, you shoot them from depth to mark position prior to surfacing
Safety Sausages, essentially the same as DSMB's, but the difference is that DSMB's will usually be closed with an OPV vs. either an open bottom, or a closed design for surface use only.
Now, here is the VERY important difference. SMB's are used to mark your position to local traffic. DSMB's are generally to mark your position on your safety stop because you are deep enough where overhead traffic is irrelevant during the dive, but now you need the surface to know you are within striking range or whatever else you are signaling. Neither of these have to be enormous, just big enough to make people aware of your position, 1m for DSMB's is common, SMB's can be smaller, 12x12 is minimum size for the flag in Florida so most are that size, and with the buoy and mast, they are usually between .5 and 1m tall. Safety Sausages are what is VERY important that ALL ocean divers need to have and be proficient at using and what I believe PADI is emphasizing in their current course. These are the ones you use when you need to be found. I'd argue that we might be arguing semantics, but it's still a difference. My SMB is different than my safety sausage, and those are different than my DSMB. If I am towing my SMB, I don't carry a DSMB, but the safety sausage stays with me.
DSMB is a DSS 1m, so it's pretty useless as a safety sausage. It is only 1m tall, it isn't that big, and while it has reflective tape on it which helps, it just isn't tall enough for Carolinas diving where the seas may be 1m or more.
https://www.deepseasupply.com/index.php?product=85
SMB is on order, it's the Mako tow float deal, pretty slick unit if you aren't flying to your destination since it can be used as a surface flotation device which is super convenient. They also have an inflatable one which is pretty slick as well
Hawaiian Hard Float | MAKO Spearguns
Safety Sausage is a Hog 72" deally
Cave Adventurers - hog safety sausage - Marianna, Florida USA - Never Undersold!
Yes this can serve double duty as a DSMB because it has an OPV, but the DSS one is much smaller profile, and is easier to carry in travel. The 72" is also a bit overkill for Caribbean type diving where the waves are pretty calm. I would choose this due to cost/performance, if I had to choose one since it can perform double duty, and is a closed design with something like 20+lbs of lift so you can hug it if you have to ditch your rig in an emergency. My Hog is in Yellow for better night visibility, vs. the DSS in Orange for day time viz.