Crystal is a type of glass, in which lead replaces the calcium content of typical potash glass. All crystal is glass but not all glass is crystal. Crystal glass actually doesn’t have a crystalline structure.
Crystal is porous. It contains certain percentage of minerals. So mineral strengthen the material and makes it thin but durable. Also it increases the weight of glass and causes light refraction.
In crystal rim is very thin but still strong.
In crystal mineral percentage varies from country to country, so the meaning of crystal changes according to country. In European community glass with 4 to 8 percent lead monoxide is called glass. Glass with lead content 8 to 10 percent is called as lead glass. Glass with 10 to 30 percent lead is called as crystal. Glass with more than 30 percent lead monoxide is called as lead or leaded crystal. While in United States 1 percent lead monoxide is sufficient to call it crystal
Some countries use zinc and magnesium oxide instead of lead, which also causes refraction. These are called as lead free crystals. They have similar refractive index as lead but they are lighter.
There is one theory which explains that crystal is rougher than glass, so that roughness creates turbulence in wine which, in turn, causes more aeration of the wine, and therefore more aromatic compounds are released.
The problem with leaded crystal is lead can leach out of the glass, especially the glasses that are often used. Exposure to lead can increase the risk of heart attack and stroke and can cause memory loss.
Although the highest quality crystal glasses provide a better wine tasting experience but they are too expensive.
Glass is nonporous and thick. Thicker glass can create distortions. It does not refract light. It is more durable and affordable than crystal. Borosilicate is a one type of glass that has high durability and has heat and scratch resistance.
It is affordable.
There is difference in crystal and glass stemware but it is up to you that how much you want to spend.