So my 2017 redshirted last year. He was listed on the 35 man roster all year as a "Freshman" and now he is listed as a "Redshirt Freshman." Last year he practiced with the team all the way and up the season, but when the season began he and his fellow redshirts were put on a different program and training regimen. Because the RS are not "in season" their training was much more rigorous and demanding. My recollection is there were about 4-5 kids who redshirted--one was a prize recruited 1B blocked by an all conference 1B senior so the coach figured he would not play and could redshirt to save a year of eligibility.
While there is a lot of focus on getting better as a baseball player, much of it seemed to be a war of wills to see which RS kids are tough enough to survive. That may be unique to his school and coach, but to the coach's credit, there are a lot of kids in the program who redshirted and are now starters and major contributors. Its more of a boot camp test and if you survive, you have a chance to contribute. The RS do not travel with the team, but at home games they have various roles from charting pitches to running the scoreboard. They are with the team, support the team, and do feel like they are a part of the team despite the differing schedules. And they do get the athlete benefits like tutors and advance registration.
Of course it is different for kids who have injuries and miss the season. Those RS are typically focused on PT or other rehab designed to get them back to full health the following season.
It may be different at other schools, so do your research. Go back and look at several years worth of rosters and see how many kids who RS survived into the next and later years. Good luck!