hi,

see in aptitude section , questions includes from reasoning, quantitative, logical reasoning, numericals   and verbal ability. best books to follow is

RS agarwal, quantitative, reasoning and verbal ability.

mental ability test is comprises of questions to check your  ability to understand the facts and significance of your behavior. capacity. ability, power - possession of the qualities, your strength and weaknesses.

Hello,
.
Mental ability and aptitude are one and same in one view. Both the section's test your IQ level. Both the sections are purely maths based concepts. Aptitude questions will be based on calendar, speed, age, distance etc.,  Where mental ability will ask you to find the answer from the following hints. Mental ability is the section which tests how good you can solve a confused question