Cruz is a sitting senator who has put forth amendments that legalize the lawbreakers albeit without a path to citizenship and increase by over 500% H-1B visas. Trump is a private citizen whose primary job is being a real estate mogul.
And you must parse what Cruz is saying now. Has Cruz said we must deport all the illegal aliens or that we need to construct a fence/wall/physical barrier along the southern border? Trump has produced a detailed position paper on immigration. Cruz has not.
I agree that Trump has energized Cruz with the immigration issue. Without Trump this issue is not as well known.
Still, Trump has apparently changed on this issue, yet that doesn't bother you a bit?