CREATE TABLE table_204_878 (id DECIMAL, "model" TEXT, "release date" TEXT, "sensor\ res. ,  size" TEXT, "lens  ( 35 mm equiv. ) \ zoom ,  aperture" TEXT, "screen\ size ,  pixels" TEXT, "dimensions\ w  ( mm )  \\u00d7 h  ( mm )  \\u00d7 d  ( mm ) " TEXT, "weight" TEXT, "features" TEXT)

what is the total number of different models ?
SELECT COUNT(DISTINCT "model") FROM table_204_878
SELECT COUNT(DISTINCT "model") FROM "table_204_878"