There are three CRT technologies on the market which differ from their mask technology: 
Shadow Mask, Aperture Grille and Cromaclear.
The 'shadow mask' is a metal sheet perforated with round holes. Cromaclear is a type of 'shadow mask' which uses slots rather than round holes. The 'aperture grille' consists of vertical stripes held under tension. 

Those different CRTs hold a number of advantages and disadvantages!

Aperture Grille

The 'aperture grille' consists of less metal, which means that more of the energy in the beam reaches the phosphor and less is converted into heat. Correspondingly they rarely tend to Purity distortions and can offer higher contrast and brilliance.
Due to its cylindrical surface this CRT offers further reduced reflections of the ambient light. A disadvantage is that this CRT is a little more sensitive to vibrations and therefore stabilised by two thin wires!

Shadow Mask, Cromaclear

These CRTs are more vibration resistant due to the perforated metal sheet - but cannot match the contrast and brilliance of an 'aperture grille'.
Moreover they tend to 'Dooming', which is caused by heating through the electron beam. Heating deforms the mask and makes it impossible for the electron beam to pass the shadow mask correctly. Therefore colour purity and brightness problems arise, especially in the corners of the screen.