(Just an FYI, this topic has already been covered about a year or two ago, I think it's somewhere down the board if you look. In any case, I'll repeat what wrote back then about what I remember from WHTT vs. Kiss108 vs. WZOU)
Back in the early 80's when I was a tween (about 10-14ish), FM radio in Boston really began to get my attention! There was Kiss, with a very heavy disco sound, with the WVBF's and WROR's in some other category, not quite WSSH or Magic, but not exactly fresh either, and then there was WHTT. HitRadio103, WHTT was the station all my peers listened to. I used to record songs off WHTT, keeping the pause button down on our Emerson stereo to keep out the elements, and then recorded the songs I liked together on a Centron C-60 (those white with orange cassettes you got from F. W. Woolworth). (These days, I wished I hadn't cut out elements, but I digress). Between 1983 and 1986, I listened to A LOT of WHTT! It was the station that had Michael Jackson's Thriller, Madonna, Men Without Hats, and Cyndi Lauper. There was never any question what the hottest songs were, because that is what WHTT was playing. WHTT was the happening thing, lots of energy, and everyone sounded like they were at a big party. Heavy on the reverb, and of course a top of the hour jingle I.D., complete with the DJ intro in front. The TV ads which ran showed a big lightening bolt, and emphasized "Power 103, WHTT." I think there's one somewhere on YouTube. Suffice it to say that WHTT was THE station of record.
Meanwhile, Kiss had their stickers everywhere, with their black background, pink lipstick and big lips, but at that point, they didn't register for me because they seemed to radical, too extreme. And, of course, there was WZOU "The Zoo," which at the time had visibility, (it's where Live on 4's Judy Paparelli went), but also didn't register, because they just didn't seem interesting (and not at all like Top 40).
Then came Summer 1986. That Spring I went away to Maine for summer camp. When I got back in August, I noticed this big dark blue and green sign just before we crossed over the Tobin on I-93 South: "The New Q103, Boston's Quality Rock." What was that? How were they on the air next to WHTT? What I realized later is they had flipped to this new station, which also was very uninteresting. It wasn't even really rock (that might have been ok, even WBCN was more entertaining than WMRQ).
That fall I leared to adjust my listening habits. "The Zoo" was now "Z-94," (or sometimes, they called themselves "Z-O-U") and they seemed to have taken over the same kind of wall-to-wall Hits format that WHTT had. Kiss 108 had also jumped in to take over from HTT's audience, and this created a true war that lasted until after I left in 1988. Both Z-94 and Kiss108 were Top 40, but that's where the similarities ended. WZOU abandoned the reverb that WHTT had, but kept the jingle and element heavy attitude. Z94 was a very disciplined format that had a very tight rotation. The Top 10's were repeated every 2 hours, and all 40 every 3 or 4. There were few (if any) "remixes" during the 86-88 era, everything was exactly as released. No backselling at all, no dead-air allowed what-so-ever. And everything was heavily processed (and remained so even after flipping to Jam'n' as I understand it). "The Madam" (Karen Blake) sounded similar to "Lady D" and was the most distinguishable voice on the station.
Kiss 108 took the opposite approach, very light on the jingles (at least initially), heavy remixes (especially after 9pm), cuts-ins througout the day with live events updates. DJ's like Uncle Dale and Lady D frequenly were allowed to mention their mistakes and talk without music beds, and backselling was the rule, not the exception. Everything on WZOU's playlist was on Kiss's, but not everything on Kiss's playlist was on WZOU's.
That last piece was the single biggest difference! You never really knew what Kiss 108 was going to do, they were going to play Top 40, sure... But, they were also going to throw in an Oldie or two, a Disco track, or an old Album Rock song from the 70s. David Bowie and Aerosmith, staples of WBCN also got airplay on Kiss. There were more rap songs, louder rock songs, and processing took a different direction on Kiss! WXKS FM was much dryer and heavier on the base than WZOU's "perfect" processing sound.
Of course these days, it is Kiss that is the so-called "disciplined" CHR, but it is much debated as to whether that's out of program direction or just budget.