Hello Aspirant,

Yes for CUET UG and JEE-Main syllabi are different. In CUET UG the syllabus consists of only class 12th syllabus but in JEE-Main the syllabus consists of class 11th as well as of class 12th syllabus.

For JEE-Main complete syllabus is mentioned below and for CUET UG I will put the link below from which you will be able to check out the CUET UG syllabus :+

Mathematics  
> Complex numbers and quadratic equations
> Matrices and determinants
> Sets, relations and functions
> Mathematical induction
> Permutations and combinations
> Mathematical reasoning
> Limit, continuity and differentiability
> Integral calculus
> Three-dimensional geometry
> Differential equations
> Binomial theorem and its simple applications
> Sequence and Series
> Vector algebra
> Statistics and probability
> Trigonometry
> Co-ordinate geometry

@Physics  
> Physics and measurement
> Rotational motion
> Thermodynamics
> Kinematics
> Work, energy and power
> Properties of solids and liquids
> Gravitation
> Laws of motion
> Oscillations and waves
> Electronic devices
> Kinetic theory of gases
> Current electricity
> Communication systems
> Electromagnetic induction and alternating currents
> Magnetic effects of current and magnetism
> Optics
> Electromagnetic waves
> Atoms and nuclei
> Electrostatics
> Dual nature of matter and radiation
+Experimental skills

@Chemistry  
Physical Chemistry 
> Some basic concepts in chemistry
> States of matter
> Atomic structure
> Chemical bonding and molecular structure
> Chemical thermodynamics
> Solutions
> Equilibrium
> Redox reactions and electrochemistry
> Chemical kinetics
> Surface chemistry
Organic Chemistry 
> Purification and characterization of organic compounds
> Hydrocarbons
> Chemistry in everyday life
> Principles related to practical chemistry
> Organic compounds containing halogens
> Organic compounds containing oxygen
> Organic compounds containing nitrogen
> Polymers
> Some basic principles of organic chemistry
> Biomolecules
Inorganic Chemistry 
> Classification of elements and periodicity in properties
> Hydrogen
> Block elements (alkali and alkaline earth metals)
> P Block elements group 13 to group 18 elements
> d- and f - block elements
> Co-ordination compounds
> Environmental chemistry
> General principles and processes of isolation of metals

For complete syllabus for CUET UG,  kindly check out the link given below :-
https://www.google.com/amp/s/university.careers360.com/articles/cucet-syllabus/amp

I hope this information helps you.

Good Luck!!!!