This question usually arrives as a line item somebody wants explained. The honest answer is that the difference matters in specific places and nowhere else, so the useful version is knowing which places.
What actually separates them
Both are twisted-pair copper and both terminate the same way. Cat6a is built to hold a 10-gigabit signal across the full 100 meter channel. Cat6 will carry 10 gigabit too, but only for roughly the first 55 meters, and less than that in electrically noisy surroundings.
The other difference is physical. Cat6a is thicker, stiffer, and often shielded, mostly to control alien crosstalk, which is interference between cables bundled against each other rather than interference from outside. That thickness is not a detail. It changes how many runs fit in a conduit and how tight a corner the cable will take.
Where it matters for cameras, and where it does not
A camera does not need 10 gigabit. Almost no camera made needs more than a fraction of a single gigabit. If the question is only whether the cameras will work, Cat6 answers it.
The reason to specify Cat6a anyway is that the cable is the part you are least likely to replace. Everything else in the system gets swapped on a normal cycle. The cable in the walls stays. Paying once for headroom you do not need yet is a different calculation from paying for performance you will never use.
Where Cat6a earns it
Backbone runs between racks or between floors, where aggregated traffic is real. Long runs near the limit, where the margin is thin already. Bundles routed alongside power or through plant rooms, where the shielding does something. And any run into a space that is expensive to open up again.
Where Cat6 is the right call
Short runs to individual cameras in an accessible ceiling. Buildings where conduit fill is already tight and a thicker cable would mean a second pathway. Retrofits where the pathway is what constrains you rather than the budget.
The answer most buildings land on
A mix, decided by run rather than by rule: Cat6a on the backbone and the awkward long runs, Cat6 on the short accessible ones. An installer who specifies one grade for the whole building without asking about pathways has skipped the part of the job you were paying for.
Where fiber enters the conversation
Neither grade of copper solves distance, and that is the point at which fiber becomes the answer rather than a bigger copper budget. A run to a gate, a detached building, or the far side of a yard is a fiber question, not a Cat6 versus Cat6a question.
Fiber also removes an electrical problem worth knowing about. Copper between two buildings can carry a difference in ground potential, and lightning-induced surges have taken out equipment at both ends of such runs. Fiber does not conduct, so it isolates the two buildings from each other electrically as well as connecting them.
It is not the default for short indoor runs, because it costs more to terminate and cameras need copper at the end anyway for their power. But on the handful of runs that leave the building, it is usually both cheaper and safer than the alternative.
Which grade goes where is a decision Elite Security makes per run during design, not per building at the parts counter. There is more like this in the blog, and low-voltage cabling is the place to start.