Is a DSLR (Nikon D750) camera really that much better than the iphoneX? Is it worth it?

Looking to buy the D750 camera by Nikon but keep second guessing myself if it's worth it. I know many will say it depends on what you want it before but just overall, does it take better pictures because of the bigger sensor and everything they can do. What all can you do more of on the DSLR over the iPhone which looks pretty professional. Thanks so much for any advice!

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Do I get a Sigma 18-35mm f1.8 or a Sigma/Tamron 17-50mm f2.8 OS/VC for general shooting?

Do I get a Sigma 18-35mm f1.8 or a Sigma/Tamron 17-50mm f2.8 OS/VC for general(mostly travel, landscapes, studio work and some video work) shooting. I will be using the lens at night and dark situations. I ll probably even use it for event/wedding photography/videography. I have a Nikon D7200 as well as a 50mm f1.8G and a 18-140mm f3.5-5.6 VR lens.

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Nikon D5300 focus noise?

Nikon D5300's makes a weird noise when autofocusing. Does it do this with the VR II lens? Or only with the VR I lens

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