Geographical distribution of malaria and tuberculosis
The statement in the question about the current distribution of these diseases is not strictly accurate, as shown by the graphic below.



[Malaria graphic: Wikipedia user, Percherie (2006); TB graphic: Corbett et al. (2003)]

However there is no disputing that the contemporary and historical geographical distribution of these diseases differ. Why?

The crux of the answer is that this is because of the different agents that cause these diseases. Malaria is transmitted by certain mosquitoes and is therefore restricted to places in which these mosquitoes are found. TB is a bacterial disease, the geographical range of which is determined by human contact under conditions which favour its transmission.

To expand:

Malaria is transmitted by Anopheles mosquitoes, especially in Africa by Anopheles gambia together with the Plasmodium falciparum parasite. One of the factors determining the mosquito habitat is standing water and the elimination of malaria from Southern Europe followed drainage of the marches and swamps in which it breeds. 

That is not to say that this is the only factor in the elimination of the malarial mosquitos from certain parts of the world in recent historic times. For example malaria has not been eliminated from Africa partly because of the cost and logistic problems of implementing programmes of eradication using drugs etc.

Tuberculosis (TB) in humans is caused by the bacterium, Mycobacterium tuberculosis. Its airborne spread was favoured by the crowded conditions in cities following the industrial revolution, and its elimination fostered by improved living conditions and the development of antibiotics in the twentieth century.

Footnote: Some Factors affecting Malarial Outbreaks in Africa

A section from an article by Tarekegn A. Abeku, entitled Response to Malaria Epidemics in Africa, is relevant:


  In highlands, transmission is unstable due to fluctuations in temperatures that are normally low. Temperature affects duration of the sporogonic cycle of the Plasmodium parasite within the Anopheles vector, survival and feeding frequency of the adult female, and duration of the aquatic stages.


and


  Semi-arid areas, on the other hand, have mostly warm climates, and epidemics are associated with anomalous rainfall, which causes increases in vector breeding and survival.