This is where common names get confusing;
The commonly named Chinese Algae eater is a "sucker mouthed" fish - Gyrinocheilus Aymonieri, however it is also named by the UN FAO as the Siamese Algae Eater (a.k.a. Honey Sucker, Sucking Loach);
The commonly named Siamese Algae Eater is actually from the Carp fmily - Crossocheilus siamensis.
Similar body shapes on both, but the Chinese has a sucker mouth (like Plecs etc.) & the Siamese has a grazing mouth with short barbels, not related at all.
Both will eat a certain amount of algae, depending on the type of algae present - they don't eat everything and certainly not algae exclusively. Many people are disappointed that they buy these fish & the problem is not cured.