Fujifilm X-H1 + XF 16-55mm f/2.8 advantages over A7iii + FE 24-105mm f 4

Crgln wrote:

(I've posted a similar question on the Sony forum, but expecting it is more likely to get responses from Fujifilm owners here):

For what objective reasons (i.e. beyond personal preference or lack of experience with Sony) would you recommend a budding photographer to buy an X-H1 + XF 16-55mm f/2.8 camera+lens combo rather than a Sony A7iii + FE 24-105mm lens combo?

I'm looking in the $3k-ish range for me son, a photography student. He is most motivated by outdoor photography, creative studio sets, and finding unique shots. He's also looking at paying gigs of people shoots and weddings (1 wedding down). He edits currently with Lightroom.

Love to hear why you might recommend the Fuji combo over the Sony combo.

Also, if anyone can help me understand:

How does one compare the specs on a Full frame lens with an APC-S lens; specifically how these two line up (at similar price points) for actual zoom, depth of field, and low-light effectiveness?

Thanks so much!

The forum members have given great comments, but I can't resist offering my 2 cents (a sign of my own vanity).  I just went through a similar decision - for full disclosure, I used to shoot the Sony A99II (a-mount), but it became clear to me that the a-mount line was dying off slowly (no new lenses or camera updates) in favor of Sony's mirrorless/e-mount lineup, so I sold off my a-mount gear.  I really went back and forth and agonized over the Sony A7III vs the Fuji X-H1.  I ultimately went with Fuji.  
You will not go wrong with either the A7III or the X-H1.  They both can produce stunning images. For the A7III, you might also consider the Tamron 28-75 F2.8 lens).  Other posters have noted that Nikon is soon to announce a full-frame mirrorless camera (this week, I believe), and of course there are a range of other fine DSLR and mirrorless cameras.
Buying a camera is a personal and expensive decision, and what is right for your son is not the same as what is right for others.  Every photographer has their own preferences on what features are really important to them, and what kind of interface they enjoy using.  If possible (if this isn't a surprise birthday gift), you might want to involve your son in the decision, just to avoid future disappointments.
The other thing to consider is that you are not buying just 1 camera and 1 lens.  You are buying into a whole ecosystem,  of lenses, lighting and other accessories.  When I approached my decision, I added up the costs of different lenses I wanted in each platform.  I looked at both new and used (from a high quality retailer, like Adorama or B&H) lenses .  For me, I found that could get the combination of lenses I wanted in Fuji at a lower cost than with Sony.  But it is dependent upon what lenses you might want.  For me the system costs (as opposed to just the camera + standard zoom lens) were lower with Fuji.  That wasn't the only factor that swayed my decision, but it was a significant one.
As for the APS-C (Fuji) vs Full Frame (Sony) - that can become a very intense debate that is a bit indecisive and overwrought.  To compare focal lengths, you apply a crop factor - for APS-C cameras, it is around 1.5.  So a 50mm lens on an APS-C camera (like Fuji) has a field of view equal to around 75mm on a full frame camera, like Sony.  As a general rule, if you have an identical composition in your photos, and you compare an identical photo shot with a full-frame camera vs an APS-C camera - the image shot with the full frame camera will probably have less "noise" (grain in the photo - your son can show you), and you might find it easier to create a shallower depth-of-field (the crop factor applies to depth of field as well, though that is again a matter of dispute - Fstoppers has a great video on sensor size, crop factors and depth of field). 
Personally, I find the image noise  difference between APS-C and full-frame to be insignificant.  The shallower depth of field can, in some situations, be a hindrance, not a help -- particularly for group portraits.  Fuji and Sony have different color renditions which is driven by both the sensors and the lenses, and whichever one you find more pleasing is very much a matter of personal taste. As for the ergonomics of both cameras (and other cameras worth considering) - other forum comments cover that.  I personally like Fuji more in terms of its interface, but others prefer Sony.  I've used Sony in the past and found it perfectly serviceable.