Answer:
There is no short answer.
Step-by-step explanation:
The blood flow speed in the aorta is about 30cm/s whereas in the capilaries it is around 1-1,5 mm/s. The reason why this is happening is because the capilaries are much smaller and thinner than the aorta and they are not as durable to those conditions. The total blood flow is the same but the rate is not so that the blood pressure can be kept in balance throughout the whole body.
I hope this answer helps.