A: An excellent word study question! When attempting to study words from the text it is necessary to analyze the word being studied in the original language (in this case Greek) as attempting to look up the words in English will often produce erroneous results.
For example, in English the word petition has within its range of meanings things that are certainly not within the scope of meanings for the Greek word (i.e. “a sheet that is signed to demonstrate agreement with some principle or desire for some social action to be taken” is part of the range of “petition” but not of the Greek deesis from which “petition” is translated).
The word most commonly translated as “prayer” in our English Bibles is proseuche, which appears 36 times in the New Testament (NT) in one form or another (for the purposes of this study, we are only examining the usage of these words as nouns – the verbal forms will not be included).
The word translated “petition” in Philippians 4:6 (“supplication” in KJV and NASB) is translated from deesis, which appears 18 times (in 16 different verses) total in the NT in some form or another. This word is likewise translated as “prayer” in most instances, e.g. Luke 1:13 (cf. NIV and NASB); Luke 2:37; Luke 5:33; Romans 10:1; 2 Corinthians 1:11; 2 Corinthians 9:14; Ephesians 6:18 (deesis occurs twice in this verse; once as “praying”); Philippians 1:4 (deesis occurs twice in this verse; KJV renders “prayer” once and “request” on the second occurrence); Philippians 1:19; 1 Timothy 5:5; 2 Timothy 1:3; Hebrews 5:7 (an interesting verse because deesis is translated simply as “prayers” and a different word, hiketeria, which appears for the only time in the NT in this passage is translated as “supplications/petitions”); James 5:16; and 1 Peter 3:12.
If you were counting, that means that the word for “petition” in Philippians 4:6 occurs 18 times (in 16 different verses) in the NT, and is translated as “prayer” 15 of those times!
A superficial analysis might lead us to conclude that these words are simply interchangeable. However, this would be a mistake as in the three instances where deesis is translated differently than proseuche, the reason is that both words appear in the verse: see Ephesians 6:18, Philippians 4:18 and 1 Timothy 2:1. These three verses demonstrate that there are different nuances to each word that warrant both being included (and a third word, enteuxis, translated as “intercession” which appears in 1 Timothy 2:1 and once more in 1 Timothy 4:5).
After collecting all of the data of word usage in the NT, we are left with four different words that have similar usage and contexts: proseuche, deesis, enteuxis, and hiketeria. While the example verse given only uses two of these words, it seems like the heart of the question wants to know the differences between all of these usages in the NT.
The first, proseuche, is the most commonly used word in the NT for “prayer” (as mentioned above, appearing 36 times in the NT). As the broadest term, proseuche, covers the entire range of “communication with God.” As Christians, we have a tremendous privilege to communicate with God and this communication can take many different forms and tones. In general, proseuche refers to such communication.
The second most common term for prayer is deesis (occurring 18 times in the NT). The most common translation is simply “prayer” but when paired with proseuche this word is often translated “supplication/petition.” Deesis is a stronger word than proseuche and indicates more urgency and fervency on behalf of the pray-er (the one communicating with God).
Here’s an example of the difference between these terms: I may commune with God as a believer and say things like, “Thank you, Lord, for that beautiful sunset!” In this case, there is no urgency. Instead, it is a general communication with the Lord and an expression of thanksgiving and personal devotion. Proseuche would rightly be used for such a communication.
In contrast, if I were to be in a difficult situation and was earnestly seeking direction from the Lord, I may pray (deesis) with more urgency saying, “Lord, please give me the wisdom I need for this situation!” Such an example of deesis is found in James 5:16 (praying for healing). If you peruse the 18 occurrences of deesis in the NT, you can see there is a weightier sense of urgency than a simple prayer of devotion or thanksgiving in view. Although still rightly translated as “prayer” in many of these instances, there is a heavier connotation to the usage.
The third word, enteuxis, appears only twice in the NT (1 Timothy 2:1 and 4:5). This particular word has a nuance of “intercession” or meeting with God on behalf of someone or something else. Again, all intercession with God could rightly fall under the umbrella of proseuche and certainly some intercession with God will carry a sense of urgency as with deesis, but enteuxis is distinctive in the fact that the object of the prayer is not the individual doing the praying. In 1 Timothy 2:1 the object is other people (urging believers to intercede for “everyone”), while in 1 Timothy 4:5 the object is food.
All three of the above words are used in a row in 1 Timothy 2:1.
Lastly, the word hiketeria appears only once in the NT and is translated in most English Bibles as “supplications” but in the NIV as “petitions” (Hebrews 5:7). This is the most intense and heaviest of the words relating to prayer and is only used of the prayers of our Lord in the garden prior to His passion.
When taking a step back and looking at the usage of these terms, we can better understand how it is that we are to pray without ceasing (1 Thessalonians 5:17). The command to “pray” is related to the word proseuche, meaning we are to be in communication with God without ceasing. We can speak with Him in a general way expressing our joy and thanksgiving for His activity in our lives, we can speak to Him about the urgent and pressing matters in our own life and in the lives of others, and we can even come to Him in our darkest and most trying situations. The command to pray (proseuche) covers all of the possible scenarios of life and encourages us that God is always interested in communing with us. How cool is that?