IPMAT has 2 sections Quantitative Aptitude and Verbal Ability. Now QA has 60 marks allotted and VA has 40 marks. Each correct answer gets you 4 marks and a wrong answer takes away 1 mark in the form of negative marking. Though there has been no official release of any syllabus, based on examinations over the years, it has been concluded that few topics are the most covered,

QA:

Number system, LCM & HCF, Percentage, Quadratic Equations, Binomial Theorem, Functions, Mensuration, Permutation and Combination, Probability, Profit, Loss and Discounts, Simple and Compound Interest, Progressions, Ratio and Proportion, Mixtures and Alligations, Logarithms, Time, Speed and Distance, Time and Work, Trigonometry, Geometery, Problems on Ages, Series and Unitary Method, Set Theory, Data Interpretation and Equations.

VA:

Vocabulary, Reading Comprehension, Grammar, Sentence Rearrangement, Sentence Correction, Sentence Completion, Correct Usage of words and phrases and verbal analogies.

UGAT has English Language, Reasoning and General Intelligence, Numerical and Data Analysis, General Knowledge, Service Aptitude and Scientific Aptitude sections.

English Language: Synonyms and Antonyms, Active and Passive Voice, Direct and Indirect speech, Nouns, Verbs, Adjectives, Pronouns, Idioms and Phrases, Para jumbles, Spotting Error, Direct and Indirect Speech, Spelling test and Sentence improvement, Substitutions, Joining sentences, fill in the blanks

Reasoning and General Intelligence: Analytical and Logical reasoning, Puzzles and riddles, Data sufficiency, Inequality, Blood relations, Seating arrangements, Direct Based questions.

Numerical and Data analysis: Problems on numbers and series, Linear questions and quadratic equations, Matrices, Time and work, Pipes and Cistern, Time, distance and speed, Boats and Streams, Problems on trains, Profit and loss, Ratio and proportion, Simple and Compound interest, Ratio and Proportion, Simple and Compound interest, Percentages, mixtures and alligations, ages, average, Simplification and approximation, mensuration, indices and surds, probability, permutation and combination, data interpreation.

General Knowledge: Current affairs, General Knowledge, Indian Politics, Indian Economy, Famous books and authors, Foreign relations, Business related topics.

If you look at the syllabus for both the exams, they are more or less the same. So you can prepare for both at the same time.