First off, let’s discuss what carries over from the GRE to the GMAT.
QuantThe good news is that the actual quant topics, such as linear and quadratic equations, roots and exponents, number properties, inequalities and absolute values, functions and sequences, probability and combinatorics, ratios and percents, rates and work, unit conversions, general number skills, estimation, statistics and overlapping sets, and geometry, for example, are tested on both the GMAT and the GRE.
That being said, you’ll have to familiarize yourself with answering Data Sufficiency questions (DS) as opposed to the GRE counterpart (Quantitative Comparisons). The GMAT’s DS questions give you initial information in the question stem and pose a question about that information. Then you are given two statements, each of which provides additional information. Your job is to determine whether the information in each or both statements is sufficient to answer the question posed in the question stem. DS questions don’t test JUST your skills in the aforementioned quant topics; they also test your skill in considering the implications of pieces of information designed to trap you into selecting the most obvious answer. So, DS questions may post the most significant challenge in taking the GMAT after preparing for the GRE, as without training to answer such questions, you may struggle to answer them efficiently or correctly.
VerbalUnfortunately, there is less carryover from GRE verbal to GMAT verbal than there is quant carryover. Both the GMAT and GRE test Reading Comprehension and Critical Reasoning; however, on the GRE, Critical Reasoning is referred to as “single-paragraph Reading Comprehension.” That being said, one major difference between the verbal sections of the GRE and GMAT is that the GRE focuses on vocabulary (within Text Completion and Sentence Equivalence questions) and the GMAT focuses on grammar (within Sentence Correction questions). Although you may have mastered GRE verbal, if you find that your grammar skills are lacking, you may have some trouble with GMAT verbal.
Regarding prep courses, in addition to seeking advice in this thread, take a look at the GMAT Club reviews for
the best quant and
verbal courses, and also read through some
GMAT success stories to see what materials have worked well for other test-takers.
Also, would you like some general advice on how to improve your verbal and quant skills?
You also may find it helpful to read this article about
how to score a 700+ on the GMAT.
Good luck!