i have an older copy of one of carpenito's careplan books and i like it a lot. in fact, it was the first careplan book i ever purchased. she may have been one of the first nurses to publish a book of care plans. i've noticed that to keep up with the times she has now got a nursing diagnosis book in publication. i haven't actually seen a copy of it, however.
what i can tell you is that ms. carpenito has been an active member of nanda for many, many years. no one knows nursing diagnosis as well as she does. some of her previous books had assessment forms in them as well as clinical pathways of care which are another style of care planning that some facilities subscribe to. she is one of the only authors i know of that has published anything commercially on clinical pathways of care.
some of the large booksellers or college bookstores of where there are nursing schools may have copies of her books that you can look at before making a decision to buy.
the difference between a care plan book and a book of nursing diagnoses is that (and you can confirm this by looking at the table of contents on barnes and noble or amazon websites) the nursing diagnoses books list all the nursing diagnoses alphabetically and give each their own chapter. within the chapters they will often include the nanda information (definition, related factors, defining characteristics, noc outcomes, nic interventions and sometimes references) and any other things that might be unique to that particular author.
please understand that a book of nursing diagnoses is and should be used as a reference book. it presumes that you know the nursing process and the elements that go into formulating a nursing diagnosis. i don't know if carpenito has started to include a cross index of signs, symptoms and medical diseases like the ackley/ladwig nursing diagnosis book does, but i can tell you that the ackey/ladwig book (nursing diagnosis handbook: a guide to planning care, 7th edition, by betty j. ackley and gail b. ladwig) is a bigger seller per the figures i've seen on barnes & noble's website. that cross index in the ackley/ladwig book is probably it's biggest selling feature because it gives you suggestions for nursing diagnoses to use with specific patient conditions so you don't have to search all through its pages trying to match symptoms to the correct nursing diagnosis. this is a very useful tool when you are new to writing care plans.