Probably more info than you wanted:
OU is much larger and VERY sports centered. Lots of partying, especially during home football games, lots of drinking! Frats and Sororities are a HUGE deal. There is some ethic diversity but not as much as many other colleges, most of the students come from OK and Texas but there are several out of state and international students. (61.1% white, 11.3% Hispanic, 9% multi, 6.3% Asian, 5.4% AA, 5.2% international) I don’t think anyone in the LGBTQ+ or out of state would feel uncomfortable. I think the Meteorology Program is great and the National Weather Center is located on campus the Music Education program is very good too. They also have a great GEO Science and Petrol engineering program and some aviation programs that I don’t know much about. My daughter was only looking at schools with meteorology programs and she considered University of Miami, Florida State, Cornell, and Texas A&M.
In the grand scheme of things UTD is a very young college and not as steeped in traditions and rituals as many universities, UTD was originally started as a graduate research college and only stared enrolling freshman in 1990. UTD is a smaller very modern campus with lots of new buildings, it is very tech centered and research oriented. It hasa great Neuroscience science and pre-health programs that give students clinical experience at UT Southwestern Medical Center. UTD has a very high acceptance rated to medical schools. Their Physics department is small but very impressive and their CS programs are very well regarded. I’ve heard they have a pretty good Business program but I don’t know much about it.
There’s not enough on campus housing to meet the demand so many students live in off campus apartments, though NMS get priority housing and usually stay on campus all four years due to their stipends. UTD is very welcoming of the LGBTQ+ community and offers the option of gender inclusive housing and has a very active LGBTQ+ service center. There are tons of student clubs and a few Sororities and Fraternities but it isn’t a huge focus. Most students come from Texas but there are many from out of state and international students too, there is a very large Indian/Asian presence (39.5 % Asian, 27.4% white 17.1 Hispanic, 5.1% AA, 4.2% international, 4.1 multi). Students tend to socialize in smaller groups and the campus seems ‘quite’ on the weekends. It is a very academically focused campus. They have some sports like baseball/softball and soccer but the biggest sports are Chess and E-sports. UTD is considered a nerdy school and the students there are proud of that:-) My sons at UTD had more choice/flexiblity as to the honors classes they could take to fulfill their requirements and the honors classes where smaller at UTD than at OU.
My sons considered University of Illinois Urbana-Champaign, MIT, and were auto admits for Texas A&M and UT Austin. UTD admits by major unlike TAMU. We are local to UT Austin and the kids have many friends attending there, they were put off by the stories from their friends of not being able to get into required classes to graduate on time and being limited in the number of CS class they could take per semester. Texas A&M doesn’t offer a very straight forward NM package, it’s a combination of many other scholarships but every NM student I know that has gone there has ended up with a full ride or pretty close to it. But having to take “weed out classes” to get into your major was a big turn off. UTD admits by major and doesn’t have weed out classes. They focus on student success and offer lots of free tutoring for freshmen/sophomore classes. Students are encouraged to seek tutoring not because they’re failing a class but also to raise their B to an A.
It’s hard to describe “vibe” I strongly encourage you to visit all the schools on your student’s list and go to UTD’s Scholars Day if you can manage it. UTD is a growing school. It’s located in the North Dallas suburb of Richardson so it’s a very safe campus but close enough to Dallas to enjoy the big city. You’re more likely to find students at UTD playing DnD or hanging out with their study group on the weekend than at a party or a football game like you would at OU. Since you’ll be out of state you might want to look at the transportation cost to and from the universities on your list. It’s likely easier and cheaper to get to Dallas than Norman/OKC. Also the DFW metro is huge and there are many, many more opportunities for internships of all kind than in the Norman/OKC area.
Random info: your student will need to pay federal income taxes on the amount of their scholarship(s) that exceeds tuition and books and required fees, this is true where ever you go. At OU, since the scholarship is from the state of OK you also need to pay state income taxes on that portion of the scholarship even if you are out of state. This isn’t a lot of $$ just a hassle. In Texas there’s no state income tax:-) Both OU and UTD will allow you to keep any outside scholarships that don’t state they aren’t explicitly for tuition only (so long as you aren’t also receiving need based aid). Also UTD didn’t require FAFSA for National Merit but OU did.