Despite the assurance of the editors of the of The Times-Chambers Essential English Dictionary (1997) that the forms of English spoken in Singapore and Malaysia have more in common than not, it is not clear if they will remain what the editors term "sub-varieties of a larger distinct variety of English known as . . . Singaporean and Malaysian English" (vii), or if they will continue to diverge. Three factors might prevent the two sub-varieties from diverging very much -- their common origin, the countries' geographical proximity, and the "continued close contact" between their peoples.
On the other hand, English has a different status in each country, in Singapore serving as the chief official language and the language of instruction in a country largely composed of Chinese speakers, and in Malaysia serving as an important examination subject but not as the chief language of instruction.
After independence from Britain in 1957, and especially after the separation of Singapore from Malaysia in 1965, the educational policies of both countries began to diverge. In Singapore, the bilingual education policy ensures that pupils are equipped with a knowledge of English and (depending mainly on their ethnicity and family background) one of the other official languages, ie. Mandarin Chinese, Malay or Tamil. While these languages are taught in the classroom, English remains the primary language of instruction. However, since three-quarters of the Singaporean population are ethnically Chinese, the Chinese language (especially Mandarin and Hokkien) is likely to exert a strong influence on the development of Singaporean English. Where this influence is felt, there is a noticeable trend in the media to adopt Mandarin-derived terms (eg. hongbao or 'red packet') in preference to traditional non-Mandarin equivalents (ie. angtow) which are nevertheless popular in less formal situations. [vii]
Malaysian educational policy, in contrast, emphasizes a knowledge of Malay, the language of instruction for almost two decades. "Malay therefore exerts a continuing influence on the development of Malaysian English" (vii), which is widely used in the private sector, particularly in business.
The Times-Chambers Essential English Dictionary (TCEED2). 2nd edition. Singapore: Federal Publications/Chambers-Harrap, 1997.