what determines which turbo inlet pipe you have?

[devonkyle77]

what factors in to whether you have the turbo inlet pipe like this
(pic courtesy of paul2x)


the item on the far left of course in that pic

or this kind of inlet pipe (pic courtesy of nka203)


the item in question is on the right in this pic

i apologize if this is simple but i am admittedly a beginner with this turbo stuff.