Receptacle <-- receives something
Container <-- contains something
Sender <-- sends something
A receiver uses his receptacle to receive something. Then he puts it into his container (memory) to keep it contained and safe.
http://www.dictionary.com/browse/receptacle
1375-1425; Middle English (< Old French) < Latin receptāculum reservoir, equivalent to receptā(re) to take again, receive back (frequentative of recipere to receive ) + -culum -cle2
There are many cases where they are interchangeable, to be sure. "I like to ski" and "I like skiing". But they are not the same. "I spent the afternoon skiing" is a perfectly good sentence. "I spent the afternoon to ski" is very much not.
"To ski" is the infinitive. It can still be infinitive without that to, such as in "do not laugh". That can be used as a noun reflecting the activity the verb refers to.
Another nonfinite form is the gerund, a form used mainly as a noun to reflect the activity the verb refers to. That is presented as the -ing form. In that usage, it may be interchangeable with the infinitive.
The third nonfinite form, or set of forms, is the participle. One of those is the progressive participle, sometimes called the present participle (notwithstanding the fact it can be used for past and future constructions), and reflects a verb whose process is (or was, or whatever) ongoing. That is used to form the present progressive ("is skiing"), among others. In that usage, it is not interchangeable with the infinitve.
Best Answer
There are things we need to do, and there are things we should do. Think of "needs" as requirements, while "shoulds" are recommendations.
So, if you want to convey that it is absolutely essential to remain strong, use one of these:
On the other hand, if you are recommending that we remain strong, use one of these:
And if you want to express confidence that our strength will not falter: