Maths A&A is one of two new branches of Maths in the IB, with first examinations in 2021, replacing the old Maths HL, Standard & Studies. Maths A&A is more naturally similar to the old Maths systems, and it is a relatively fair appraisal to suggest Maths A&A HL is simliar to the 'old' HL, whilst Maths A&A SL is quite similar to the old Maths Standard SL. There is some new, very interesting material, but with less of a focus on applied Maths (statistics, probability), so only pursue this option if you like understanding Maths from first principles, and not someone who would rather be using their calculator and spreadsheets to solve problems.

Maths A&A is a natural pathway to STEM subjects - students keen to study Physics, Chemistry, Engineering and other subjects at university. The skills you develop through this course are naturally broad, though perhaps more theoretical than the equivalen A&I course.  Many universities do have a preference for A&A over A&I, particularly at HL for prestigious institutions.