To answer that question we need to understand what those words mean when understood in their original context.

Elders

In the New testament the term “Elder” refers to leaders in general – see 1 Timothy 5:17 which implies that not all elders preach and teach but some are primarily involved in other areas of church governance. “The elders who direct the affairs of the church well are worthy of double honour, especially those whose work is preaching and teaching.” 1 Timothy 5:17 (NIV) The Greek word used for elder is presbuteros see Acts 11:30, 14:23, 20:17 and Luke and Paul seem to use this word when talking generally about those in leadership positions within the church. However there are two other words used to describe leaders in the New Testament and these are diakonos and episkopos. Scholars believe these to be two distinct roles within the broad category of church leadership.

Deacons

The word deacon is derived from the Greek word diakonos, which simply means "servant" so Deacons literally serve the congregation. Traditionally Deacons are given service / administrative roles in church government as opposed to upfront teaching ministry roles. But as 1 Timothy 3:9 states these men must also be clear on the central beliefs of the faith. Indeed the men called to serve at tables (literally to diakonos) in Acts 6:1-7 were also able to teach, evangelise and perform wonders among the people (see Acts 6:8, 8:6; 8:12).

Overseer

Episkopos is translated as, bishop or overseer. The bishop / overseer seems to have more of an emphasis on word ministry – as they must be able to teach (see 1 Timothy 3:2). Specifically they are to:

1. Settle disputes and or questions relating to belief and practice – in other words must be able to teach and discipline the church. See Acts 15:1-2 and 1 Timothy 3:2.
2. Devote themselves to prayer and to teaching the word (Acts 6:2-4)

When appointing anyone to a position of leadership in the church it is essential that their character matches the qualifications found in the New Testament. However some will be more gifted to serve through tasks such as administration rather than more public activities such as preaching. In comparing the qualifications in 1 Timothy 3 for overseers, in verses 1-7 and for deacons in verses 8-13, there doesn’t seem to be much difference. This is because the qualifications speak more to the issue of character than they do of role. The characteristics required for church leaders are set out in 1 Timothy 3:1-13, Titus 1:1-9 and 1 Peter 5:1-3.