Fard is only the obligatory (2rakaa fajr + 4 zuhr + 4 asr + 3 magrib + 4 ishaa)
All other prayers are Nafl.
Now the Nafl prayers can be given the name of Sunna when it is "mentioned in particular" by the prophet may the peace of Allah be upon him; as for examples the 4rakaa before Frad of zuhur or the 2 rakaa before Fard Fajr "sunnat of alfajr" or the 2 rakaa after fard magrib "sunnat magrib".
These prayers are Nafl but we call it "sunnat of zuhr" , "sunnat of Fajr" , or some other prayers mentioned in the previous answer as " al istesqaa": rain prayer; During times of droughts.
"al istekhara":asking Allah to choose the right for the muslim in a specific situation.
"Kusuuf Prayer" :Eclipse Prayer; This Prayer is congregational and perfomed only when an eclipse has happened.
So sunna is the Nafl which mean not obligatory, but this voluntay prayer "Nafl" is mentioned in particular by the prophet may the peace of Allah be upon him so we call this nafl as "sunna". If someone want to pray more , or in other times we call it Nafl and we then dont use the word "sunna" but we say nafl or general nafl . general nafl mean any voluntary pray which is not related to a time or a situation that mentioned in particular. For example After Fard of Zuhr someone may pray more than 2 or 4 rakaa , 14 rakaa for example , these prayer are Nafl , we call it only Nafl. When we speak about a voluntary pray which is mentioned in particualr as the 2 rakka after Zuhr we call it Sunna which is also nafl. Nafl mean something additional and voluntary or complementary.
Duha : is a pray before-noon (from 2 - 12 rakaa, every 2 rakaa are separated ofcourse). it is before-noon "not the Afternoon" .
The time for Doha pray is generally any time after sunrise untill noon which is the time of zuhr. Accurately, the time of Duha start from about (7 or 8 -20 miutes after sunrise) untill about (10-20 minutes before Zuhr time ).
The few minutes after sunrise and few minutes before Zuhr is the time when the pray is generally not allowed.
Witr is a word to mention the odd pray after the 2 or more rakaa after ishaa and before Fajr. any time after isha and before Fajr is the time for this odd pray which generally performed after the 4rakaa Fard Isha and then 2 rakaa voluntary "sunna of after ishaa" and then the Witr . The witr should be generally 3rakaa. It can be less as 1 or more than 3 also , but in general speaking it is 3 rakaa.
All these are voluntary . Fard is only obligatory but the prophet used to do daily and always some of these prayers particularly which is before and after some of fard as (2 befor fard fajr- 2 after magrib, 2 after isha ..etc.) .
Tahajud is word can be used for any prayer performed at night afeter the one sleep and then wake up at night to pray partucularly at the last third of nught before fajr.
Qiam al-lail is any pray at night including tahajud but generally it used for prayers at night after ishaa but before sleeping.
There is nothing can be called "the midnight prayer " but may be you mean the night prayer which is the same of Qiam Al-lail. The arabic word "Lail" mean night.
All these prayers are same , if some one said no difference between them he is true to great extent.
What to read in these prayers : as same as any prayer and all are the same, very similar to Fard. every rakaa u read "Surat Al-Fatiha" and some of Quraan which may be very short or very long as u like, If some one don't know anything other than Al-Fatiha so he can read it alone, it is enough for people who do not know more.
There are some very small difference (which can be neglected if someoe don't know it)about some particular prayers which is not rotinely and daily performed as " al istesqaa": rain prayer; During times of droughts, for example.
At the end "al istekhara pray ": is a voluntary pray for asking Allah to choose the right for the muslim in a specific situationis. It is as same as any 2 rakaa, read in the first rakaa surat al-Fatiha and Surat al-Ikhlas, the second rakaa read surat Al-Fatiha and surat al-kafiroon, After u finished the 2 rakaa, you pray "make duaa" asking Allah to choose the best for you among 2 things for example which you are worry what of them to choose for yourself, and asking allah to take away from you the thing which is bad for you. You do that whenever you should take a decision and you are worry waht is better to choose so you pray asking to help you choosing.
