These are all titles denoting a person of Islamic learning, with some cultural variations in usage.
1. Maulana was adopted, mainly in the Indian subcontinent and its diaspora, and often given as a sign of honor to the student who has completed the Dars-Nizami curriculum or equivalent.
2. Shaykh is the commonly used equivalent in the Arab world, and is additionally in regular usage in the West, especially outside of the Indo-Pak community.
3. Ustadh is used throughout the world in different capacities, and in Southeast Asia (Indonesia, Malaysia, Singapore etc.) it is used as an equivalent of the Indo-Pak Maulana, and Shaykh. In the Arab world, it has come to denote a university professor (although, it may also have a broader application). The title Ustadh has also started to gain popularity in the West, but there often, yet not always, refers to someone who has not yet completed the same level of rigorous studies as the aforementioned.
4. Common in the West is also the usage of the title Imam to denote a prayer- and community leader or scholar.
5. Mufti is mainly used in two ways, namely, that of the Indo-Pak community, which denotes someone who has undertaken successful postgraduate studies in Islamic law and issuing legal edicts, and secondly, that of the Arab world, and other nations with significant Muslim usage, where a Mufti tends to be state appointed, and the highest religious authority of the land. In the West, the usage of the title Mufti tends to follow that of the Indo-Pak community.
All the above titles, perhaps aside from Mufti (which to some extent – at least in theory – is a sign of specialization in a particular field), are purely cultural, and each culture has its own criteria for who they consider worthy of positions of leadership and titles of honor, and which titles to employ when and where.
I hope this was of some help.
May Allah Ta'ala bless you always.
Answered by Shaykh Isa Husayn Johansson