Allaah Alone is One.
As-salaamu `alaykum wa rahmatullaah wa barakatuh
Point #1:
Reading through Soorat Maryam had me thinking of various points, one of which was the repetitive use of the word فرد as opposed to the word واحد – they both mean ‘one’/single/alone etc but people tend to use them interchangeably. I wondered if there was more to this & then I noticed that throughout the Qur’aan when it speaks of Mankind being raised up and the wrongdoers brought to Allaah for judgement it says that they will come, فرادى (alone) and the word waahid is not mentioned as much.
So why is this the case if they both mean the same thing?!
Well, do they both mean exactly the same thing?
No actually, not if we dig deep enough. 
They say that:
الفرد: لا يفيد الانفراد من القرن
الواحد : يفيد الانفراد من القرن في الذات أو الصفة
In other words, the term fard has no special connotation to it, and the one who is described as being fard is one that is alone, with no special value or rank. He is completely alone and carries nothing of material gain or even honour in some cases.
This is in contrast to the term waahid which indicates that although the person is one and alone, they have شأن (status), degree and is distinguished from others. They are alone but yet they carry with them much more, like respect, honour and value.
This is remarkable considering how Allaah (`azza wa jall) always describes Himself in the Qur’aan as being ‘Waahid’ and never ‘Fard’
Point #2:
This is also the reason perhaps, that Allah says:
أَفَرَأَيْتَ الَّذِي كَفَرَ بِآيَاتِنَا وَقَالَ لَأُوتَيَنَّ مَالاً وَوَلَداً
“Have you seen him who disbelieved in Our Verses and says: “I shall certainly be given wealth and children.” [Maryam 19: 77]
وَنَرِثُهُ مَا يَقُولُ وَيَأْتِينَا فَرْداً
“…We shall inherit from him all that he talks of (i.e. wealth and children), and he shall come to Us alone (fardan)” [Maryam: 80] – i.e. without all the materialistic gains and honour/position which he had attributed to himself.
Interestingly, it also says in Soorah al-An’aam:
وَلَقَدْ جِئْتُمُونَا فُرَادَى كَمَا خَلَقْنَاكُمْ أَوَّلَ مَرَّةٍ
“And truly you have come unto Us alone (furaada) as We created you the first time…”
[al-An’aam 694]
In tafseer al-Kashaaf [by Zamakshari], it mentions that this verse actually came down regarding al-Waleed ibn al-Mugheerah who incredibly was nicknamed ‘al-Waheed’ by the people They say that he was called so due to his leadership, wealth and honour.
Subhanallaah, what a powerful message then this ayah sends to him, when Allaah says, ‘You have come to Us alone’ – using the term fard instead of waahid [so Allah has replaced Waleeds/Waheed’s honorable name into a humiliated one (Fard)].
Point #3:
If you thought that was something, see what He `azza wa jall says in al-Muddathir (in those 16 verses that were revealed about al-Waleed):
ذَرْنِي وَمَنْ خَلَقْتُ وَحِيداً
“Leave Me Alone (to deal) with whom I created Alone (waheed).”
Subhanallaah! Indeed, what a humiliation for al-Waleed ibn al-Mugheerah. Truly, Allaah alone is al-Waahid al-Waheed.
Allaahu akbar.
Differences in terms taken from: سلسة الفروق اللغوية
Source: http://fajr.wordpress.com/2008/06/04…-alone-is-one/
FOOTNOTE: Al Waleed was the father of Khalid ibn al Waleed, a Noble from Quraysh and from the clan of Bani Makhzoom. He was so rich, wealthy and honored by the Quraysh – that he was titled as al Waheed/Independent from anyone else in wealth/honor/children etc. (as explained above.)
Also see;
http://linguisticmiracle.blogspot.com/2010/04/al-walid-and-what-can-i-possibly-say.html
The Literary Miracle - al Qur'an 