are all metal halide bulbs the same??

recently purchased a 1000 watt metal halide bulb for a light thats 1000 watt hps/ MH switchable there was a hps bulb in when i purchased it and i tried putting in the MH bulb when it came and the bulb touches the hood of the light i had to bend it to get it to fit and now the glass covering wont slide back on (its a ventilated hood) are there differnent types of bulbs? did i buy the wrong one? here is a link to the bulb i bought
http://cgi.ebay.com/Prolume-Metal-Halide-1000-Watt-M47-E-MH1000-NEW-/200216509176?pt=LH_DefaultDomain_0&hash=item2e9dd57af8#ht_902wt_907

is there like a special grow light bulb or something?

Metal halide lamps have a few different shapes and sizes. They go by designations like BT-56, but for all intensive purposes there are large, medium, and narrow shaped MH lamps. Most MH lamps of the past were giant bulbs, now most are a bit smaller. The giant, like what you have, are still available but not commonly purchased. Most hydro shops don't even sell those sizes anymore. In the future if you get anything like hortilux, ushio, solarmax, digilux brand, etc, it will work for you.