I wanted to replace my tyre with the number 175/70 R13 but the seller gave me a tyre with the number 155 R13 are they the same or I should get the same number
Tyre sizes are indicated by different numbers. Take for example 205/50 R 16 87V. The first number 205 is indicating the width of the tyre in mm. 50 denotes the height of the tyre in % of the width of the tire, measured from the edge of the rim (normally called an aspect ratio). R stands for radial, 16 for the diameter of the rim in inches. 87 denotes the load capacity of the tyre (545kg max) and V stands for a certain speed index (240km/h max).
If you apply this to your case (where in fact some numbers are missing), you are comparing a tyre of 175mm width, 70mm height, 13 inch to a tyre which has a width of 155mm, 13 inch.
For your safety and for the fun of driving you should stick to the numbers that the manufacturer of your vehicle states. Usually this is printed on a sticker, mounted on the chassis in the door opening of the driver side. If it's missing there, it also is noted in the manual of the vehicle.
In general terms the width of the tyre determines the grip you get on the road, while the height of the tyre is determining the driving comfort. But you need to be aware that if your new tyres height deviates too much from the factory specified height, your spedometer will also be influenced..