I feel like you should avoid ambiguity when possible, but also be willing to glean from context when you can.
People refer to "strings" as in, a "string of characters". Or, Strings as an object of type String. Not everyone gets the capitalization correct, but you can generally tell. If I talk about "char name[]" as a string, you know what I mean. Stopping a conversation to point out that it is in fact an array of char is just pointlessly anal, unless there is a real chance the offender doesn't understand the difference and might appreciate being made aware.
Same goes for other abbreviations. You don't talk about file sizes in megabits, so a 10mb file is clearly 10 megabytes. My cable modem connection is 20mb -- that is, megabits, because that's the convention for bandwidth. If I wanted to be correct (and I usually do), I would write Mb or MB, but I won't derail a thread to point out an inconsistency when I know darn well what someone meant. (And I
definitely won't hassle someone over whether it should've been MiB or Mib instead. The difference rarely matters in typical context. When it does, clarify.)
Someone on another forum posted a reply to point out that a "tick every xx uS" is improper, as ticks are not expressed in micro-Siemens, nor micro-Samples, but micro-seconds. Good for you. Can we get on with the topic now?
In short, try to be clear. Likewise, try to be tolerant. If you genuinely can't tell -- ask. (Unless you write technical documentation. Then, it's your job -- you should try to get it right.)