As a writer for BJI, again, I'm biased... but comparing the two magazines is like comparing apples and oranges. They're both fruit (bowling magazines = good for you), but IMHO BJI takes a more holistic approach to putting together each book. You have opinion, an instructional section (featuring a monthly column by Bill Spigner, a monthly column by Tom Kouros, a monthly column by yours truly, and an ever-changing assortment of specific articles -- Grip Pressure, Breaking Down Belmonte, etc.), business news, bowling history articles, pro tour and amateur news coverage, regular features, the BJI Interview, and ball reviews. Plus, we have our annual almanac in our January issue, which is undoubtedly the most complete and accurate resource in terms of keeping track of past tournaments, award winners, etc. BTM primarily has instructional articles, a page devoted to each ball, and one or two opinion columns that may/may not be relevant to the material in the book. Occasionally, they will expand their content, but they clearly focus more on one aspect of the sport rather than many. Not a bad thing, per se, but I personally find that magazine a bit boring and repetitive at times (especially if you read the issues from the early 90's on). The same information comes up repeatedly, and if you do fancy yourself an informed member of the bowling community, you may not be impressed with what BTM has to offer (because you've heard the suggestions, the coaching remarks, before in some other guise).
But...again...I'm biased.

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