Arduino shields

hi every one
my name is srinivas. i am new to Arduino environment. i have Arduino Uno board with me and i am planning to do a project with gsm and gprs. but i am confused exactly which components i have to buy for my project need.

i've gone through net and i found the following links for gsm and gprs modules...

the following link is for GSM/GPRS modem

and the below link is for arduino shield

http://www.geeetech.com/gprsgsm-sim900-shield-board-arduino-compatible-p-610.html

is there any difference between GSM/GPRS MODEM and SHIELD functionality or any other difference ????

if i buy any one of the component from the above links will it make any difference ?????

and the following link is for gps shield

http://www.rapidsignalph.com/shop/gps-shield/

any one who is reading this post please help me out or if you have better options for components which suits for my project please suggest me..

thanks in advance....

Generally , when you post on the forum, before you start asking questions , you state your OBJECTIVE. We REALLY get tired of having to ASK people 20 questions before we FINALLY get down to what they are trying to do. I don't know why, but more than 50% of the people who post withhold more than 30% of the information we need when they do their first post. Sometimes it takes
10 posts before we find out ALL the details. For this reason, it is much more expedient to begin your post with:
Hi, my name is John Doe, and I'm new here and I was thinking it would be cool to build a WIRELESS PAVLOV SWITCH for my dog so
when he's hungry he can just step on the PAW-SWITCH and it will send me an email. Where should I start ?
In your case , we don;t know what you want the GPS or GSM or whatever for , and frankly we don't care, but in order to help you,
we NEED to know why you want these things so we can answer your questions correctly and provide you with the information you need. Asking " is there any difference ?" or "will it make any difference ?????" , leads to the question "well, what do you want to do ?" See , here we go... 20 questions....
Question #1 ....

hi sorry for insufficient data..

OBJECTIVE
-> connecting gps and GSM/GPRS modules to Arduino Uno board, and collect the current location data from GPS and send this data to the server using GSM/GPRS module. this my OBJECTIVE
-> to do this i have Arduino Uno board with me. now i am planning to buy the other modules GPS and GSM/GPRS modules..

here i got stuck , because i am confused about the GSM/GPRS MODEM and Ardino Shield
-> the below link is GSM/GPRS TTL UART MODEM-SIM900A

this i can directly connect to the Arduino board with connecting wires...

-> the below link is GPRS/GSM SIM900 Shield board arduino compatible
http://www.geeetech.com/gprsgsm-sim900-shield-board-arduino-compatible-p-610.html

this i can easily mount on Arduino board

questions:
-> is there any difference between these two according to the functionality ???
-> can i use any of these for my project need???

in my project Gps module that i want to use is having the external antenna because for better reception
for this i selected this

http://www.rapidsignalph.com/shop/gps-shield/

questions:

-> the components that i've selected will work for project ?? or any other suggestions for components which will fit for my project ????

any suggestions please share with me

thanks in advance....

Yes , that's much better. That should be enough information for anyone to answer your question.