SMS stands for Short Message Service and has a limit of 160 characters, while MMS stands for Multimedia Messaging Service and has no limit. MMS texts can also send media, such as pictures, instead of text-only messages in SMS.
SMS texts tend to go off without a hitch between phones because they have been around for so long. Every once in a while, service providers get jammed messages in their networks that slow down text transmission. MMS messages need to change their formats in between sender and receiver in order for them to end up in a readable format.
Another big difference is that almost any cellphone can send an SMS message, but some older handsets have trouble with the newer MMS format. This results in some failed message-sending attempts. MMS messages can also contain music, animation, and other forms of interactive media.
Carriers sometimes get around the 160-character limit on standard SMS texts by splitting up the text into many smaller texts. It becomes possible to send very large texts in 160-character chunks that are continuously sent for as long as necessary to send the whole message. This does get very expensive if the cellphone user does not have an unlimited text plan.