The colour of my balloons look different from the website

Latex balloon colour does not match colour in the picture.

Images are not perfect. Due to the nature of a balloon including its shiny round surface, it may not be easy to capture the true colour. Even the camera used will capture the same balloon differently.
Lighting has a huge impact on the colour of the balloon you see. This includes white vs yellow indoor lighting, or indoor vs outdoor lighting, and even time of day impacting the outdoor light.
Balloons are not inflated. Keep in mind that your uninflated balloons will appear much darker than the final colour when fully inflated, which will lighten up the colour.
Balloons are underinflated. Many decorators underinflate balloons to create balloon sculptures, but keep in mind this will impact the colour of the balloon, making it appear darker.
Balloons are of a different brand. Even though various brands produce similar colours and styles, the hue or overall colour may differ. Therefore, try and use balloons from the same manufacturer.
Balloons are of a different style. There are different styles of balloons, such as pastel, standard, and crystal for instance. The same colour in various finishes/styles will have different tones/hues/intensities.