Lyophilic sol: These are also called reversible sols. These are quite stable and cannot be easily coagulated. Example are Sols of organic substances like gelatin, gum, starch and proteins
Lyophobic sol: These are also called irreversible sols and these are unstable and can be easily coagulated due to lack of protecting layer around charged colloidal particles, they easily form a cluster. Hence, they got easily coagulated on the addition of small amount of electrolyte. Examples are Sols of inorganic substances like Arsenic (As2S3), Iron (Fe(OH)3 and platinum.