The DR number, Diederich Rank, refers to the highest number in Diederich's frequency listing, which you can see here: Diederich Ranking.
DR 125. Si vis amari, ama. ~ Note: You can find this sentiment in a variety of ancient sources, including Publilius Syrus and Seneca.
DR 125. Ut ameris, ama. ~ Note: You can find this sentiment in Martial, Epigram 6.11.
DR 125. Ut ameris, amabilis esto. ~ Note: You can find this advice in Ovid's Art of Love, 2.
DR 128. Sumus quod semper facimus. ~ Note: As often, the antecedent of the relative pronoun is not expressed: Sumus (hoc) quod semper facimus.
DR 128. Non semper ea sunt quae videntur. ~ Note: Recall that the verb "videre" in the passive, as here (videntur), conveys the notion of "seeming" in English: Things are not always what they seem. You can find this saying expressed in a poem by Phaedrus, 4.2: "Non semper ea sunt quae videntur: decipit / frons prima multos," "Things are not always what they seem: the first appearance deceives many people."
DR 128. Dicere et facere non semper eiusdem. ~ Note: There are two different ways to take this saying, depending on context. It can mean that saying and doing are not always of equal value (eiusdem, genitive of value from idem, neuter singular), and it can also mean that it is not always within the power of the same person (from idem, masculine singular) to speak and to act.
DR 131. Acta, non verba. ~ Note: As you have seen before, there is proverbial opposition between words and things (res), words and deeds (facta) and, as here, words and actions (acta).
DR 131. Factis, non verbis. ~ Note: This proverb expresses an opposition similar to that of the proverb "rebus, non verbis," which you saw earlier.
DR 131. Rebus, non verbis. ~ Note: The superiority of things to words - mere words as it were - is a popular theme in Latin proverbs. The use of the ablative without an expressed verb can be understood in all kinds of ways, depending on the context, e.g. (opus est) rebus, non verbis - we need real things, not mere words.
DR 131. Non verbis, sed rebus. ~ Note: This is an even more emphatic version of the previous proverb, beginning with the negative, and then affirming the positive: we don't need words - what we need are the things themselves.