Q:

What is the difference in meaning / nuance between ריב and תלונה? 

We frequently see some form of ריב and /or תלונה used when B'nai Yisra'el complains with Moshe and Aharon.  Examples:
Shemot 15:24 וילונו
Shemot 16:2  וילונו
Shemot 17:2  וירב
Shemot 17:3  וילן
My understanding - תלונה means a complaint, and we do see in these examples, that the people are complaining.  But in the 2nd to last example, it seems that they are complaining, as well by saying "Give us water".  Although, they are stating a direct request, here, where as in the next verse they are registering their "usual wish" of why Moshe took them into the desert. 
I understood the term  ריב means "argument", unless there is another definition or nuance, here.  When / why would oen of these 2 terms be more appropriate?  

A:

Ramban on the spot clearly explains that Riv is a full blown argument, while Teluna is just complaining. 

A:

Rav Hirsch on Beshalach 15:24

וַיִּלֹּנוּ הָעָם עַל משֶׁה לֵּאמֹר מַה נִּשְׁתֶּה

:tranlates this as

And the people murmured against Moshe, saying: What shall we drink? 

**
וילונו - לון
**

to seek shelter from hardship, hence to stay somewhere overnight, and
  מלון  an inn.  From which we get הלון על to seek redress from a
  hardship which one has to endure, to put yourself above somebody, to
  speak and spread abroad complaints about somebody, to grumble about
  somebody. 

Here they not only had no water but they had undrinkable water.  They did not realize that had they gotten to a real oasis, there would have been people there who would have objected to their coming.  However, Hashem had set up a situation where He would sweeten the water for them, but the population of the area knew that the water was undrinkable (as shown by the name) and had abandoned it.  Had they encountered people they would have panicked and run. 
Rav Hirsch then translates Beshalach 17::2

וַיָּרֶב הָעָם עִם משֶׁה וַיֹּאמְרוּ תְּנוּ לָנוּ מַיִם וְנִשְׁתֶּה
  וַיֹּאמֶר לָהֶם משֶׁה מַה תְּרִיבוּן עִמָּדִי מַה תְּנַסּוּן אֶת
  יְהֹוָה:

as

And the people contended with Moshe and said: Give us water that we may
  drink

Rav Hirsch comments:

וירב is not תלונה as in verse 3, which we found (from the meaning of
  לון) to mean seeking relief from some privation or distress that one
  is beginning to feel, but וירב is chiefly used for establishing a
  supposed or real claim to something to which one has a right, as in
  the dispute over the wells (Gen. XXVI,20).  Here they were not yet
  making any reproaches, did not refer to their requirements, but as a
  justified claim, demanded water.  Where we camp, there must be water:
  תנו לנו מים As the ן in תריבון and תנוסון stresses the second person, the retort runs: you know quite well that it is not I but
  Hashem who has led you hither, and surely you have by now had
  sufficient experience of Hashem to quietly trust to Him that here also
  He will not let you die of thirst.  In ordinary circumstances your
  demand would be quite justified, but you etc. 

Note that Beshalach 17:3

וַיִּצְמָא שָׁם הָעָם לַמַּיִם וַיָּלֶן הָעָם עַל משֶׁה וַיֹּאמֶר
  לָמָּה זֶּה הֶעֱלִיתָנוּ מִמִּצְרַיִם לְהָמִית אֹתִי וְאֶת בָּנַי
  וְאֶת מִקְנַי בַּצָּמָא:

Rav Hirsch translates as 

But when the people thirsted ...

Rav Hirsch points out that they still had water and manufactured an argument because new water was not waiting for them.  Had they waited one more station, they would have arrived at Chorev and received the miraculous well of Miriam that was to provide them with water for the entire trip.  Thus, the Torah uses the term for argument rather than recognition of a justified complaint.