Slot: positive pre-read, you will get in
Tip: coach tells admissions they like you, may or may not help you, no guarantee .
@OldbatesieDoc thanks for explaining these jargons! 
hmm, my interpretation about tips is different. Tips are for athletes that are have or exceed the average/median academic qualifications of the school so the coach only has to “tip” them in versus allocate a full roster slot.
I’ve always thought of a “tip” as everything else being equal between two students, the sport would “tip” you over the other student. As others have noted, no guarantee of admissions.
I believe the meaning of tip and slot can vary a lot by school. A former nescac coach explained it to me this way: he was given a set # of tips and slots each year by admissions to use how he wished. He could bank them or trade with other sports, within limits. Whether he used a tip or a slot depended on the student and what the admissions rep told him about the student’s chances of admission. Generally, the strongest applicants with a high chance of admission would only require a tip; the more marginal or uncertain would require a slot. But in both cases, there was no mystery for the coach: admissions would tell him flat out that a kid would only need a tip, or that another kid would require a slot. In neither case was there a guarantee that the coach could communicate externally, but everyone inside the process viewed the admission ‘chances’ of each supported candidate as equally high. (In most cases he said the athlete never knew whether he used a tip or a slot because it didn’t matter—the level of support was the same, it’s just that the slots ‘cost’ him more. And, importantly, he would never use up a tip on a kid that needed a slot…he’d rather bank the tip or trade it).
Now, I think there are other places that use the phrase ‘tip’ when what they are describing is a less formal and far less robust level of support. For example, a coach who offers to have admissions flag an application or submits a large list of athletes she ‘likes’, some of which may get admitted but many of which won’t. This is why it’s important for athletes to have frank and direct discussions with the coach, and not assume that a ‘tip’ means the same thing everywhere.
@politeperson and @makemesmart. You’re welcome. Glad to help. My S was not eager to leave the West Coast, so my knowledge of NESCAC tips and slots is limited to what I learned from a handful of conversations we had with coaches at Williams and Tufts. My understanding from the conversations we did have was that a “tip” typically gives an athlete a slight preference versus other similar applicants in the admission process. A “slot” was more of a guaranteed position. The Pomona coach did not use the NESCAC tip and slot vocabulary, but from what the coach described, my S essentially had the equivalent of what the NESCAC schools would call a tip. The Pomona coach was very direct, honest and professional throughout the process. The coach warned us up-front that while my S had a positive pre-read, that he and the team really wanted him at Pomona, and that he thought our S had a good likelihood of admission given his overall academics/athletics/extracurriculars, there was no guarantee. So we went into the process with both eyes open and luckily Pomona came through.
And yes… from what I gathered, coaches generally use tips for students that are academically well-qualified compared to other applicants, and slots for those that may need more help to make it through the admissions process. However, I’ve also heard about guaranteed slots used to entice and ensure admission for highly-qualified applicants as well, particularly at schools that have become so selective that a high GPA/SAT combo does not necessarily guarantee admission.
On Pomona, are you able to share sport, GPA, SAT/ACT and outcome on admission? S going through recruited process now.