The relationship of the command to construct the Mishkan, Tabernacle, to the narrative of the Mishkan's actual construction is quite puzzling. That is to say, in the Torah reading of Parshas Terumah, we find that Hashem commanded Moses, Moshe Rabbeinu, first to construct the holiest Keilim (Articles of the Mishkan) - the Aron (Ark) and Keruvim (Cherubs), followed by the Shulchan (Table) and Menorah - while construction of the actual Mishkan edifice and perimeter was commanded afterwards.
On the other hand, when it came time to construct the Mishkan, Betzalel reversed the order, first constructing the outer chambers and sections of the Mishkan, and constructing the Keilim last. (Shemos 38:22) In fact, the Gemara states that Moshe agreed to this order. (V. Rashi ibid.) Why, then, was the command to construct the Mishkan in reverse, with the Keilim coming first? Why did the command and the actual construction order not match each other?
Furthermore, one can question why the narrative of the Mishkan's construction details every facet of the work, for all details of the Mishkan were already presented in the initial command to construct it. Could the Torah not have simply told us that all which Moshe was commaded concerning the Mishkan was carried out by Betzalel and his workers, without repeating each elaborate step?
All of the above questions would seem to share the same answer. According to the Ramban, who posits that the command to construct the Mishkan preceded the Chet Ha-Egel (Sin of the Golden Calf), and that the construction commenced subsequent to the Chet Ha-Egel, we must understand that the Mishkan's role changed as a result of the Chet and was redefined thereafter.
Prior to the sin, the Chet, B'nei Yisroel were privileged to experience the Shechinah (the Divine Presence) almost effortlessly. The Luchos (Tablets), radiating intense holiness, kedushah, were gifted without human toil, and the Mishkan was to be an abode for the Shechinah in our midst; we were not expected to do anything to merit this state other than heed Hashem's commands and construct the Mishkan.
It is for this reason that construction of the Mishkan's most holy Keilim was commanded first, as the concept of the Mishkan was for the Shechinah to reside in our midst, and these Keilim, as explained by Chazal (the Talmudic Sages), represent Hashem's Presence. The exterior of the Mishkan was thus a mere container for the holy Keilim, which represented the immancence of the Shechinah among B'nei Yisroel; the Keilim were the primary feature of the Mishkan.
With the Chet Ha-Egel, all changed. We took Hashem's Presence for granted and no longer deserved the almost effortless exposure to the manifestation of His intense holiness, just as we no longer merited to possess the first set of Luchos, which were a supernatural object of absulute, unfathomable kedushah. Rather, the Children of Israel, B'nei Yisroe,l now needed to appreciate Hashem's Presence, and they had to work for His closeness. This is why Moshe had to personally carve the new Luchos, and why Hashem said that He would not personally accompany B'nei Yisroel after the Chet.
Hashem was teaching us that we need to put forth effort and show a desire to be close to Him.
Reflective of this new reality, the Mishkan suddently took on a new identity. It was to be a place for B'nei Yisroel to approach Hashem and seek Him. Thus, the Mishkan's structure, serving as a venue to approach the Divine, was now the primary component of the Mishkan, and the Keilim were secondary. This explains the reversal in order of the Mishkan and Keilim as featured in the command to construct the Mishkan versus the actual construction.
Thus, on a conceptual level there were really two Mishkans. One was a locus of Hashra'as Ha-Shechinah, Divine Presence, represented by the Mishkan's most holy Keilim; this was the Mishkan as depicted prior to the Chet. The other vision of the Mishkan was that of a locus for approaching Hashem, as narrated in the post-Egel accounts of the Mishkan's construction. The entire Mishkan is thus presented twice, as it was truly a structure of dual character.
This idea is borne out in Rashi (Bamidbar 7:89, from Sifri), in which he explains that there seems to be a contradiction in how Hashem spoke to Moshe in the Mishkan. On the one hand, the Torah (in Vayikra 1:1) indicates that Hashem's voice came to Moshe when he was in the exterior area of the Mishkan, implying that the voice emanated from upon the Aron (Ark) and traveled out toward Moshe; another verse (Shemos 25:22) indcates that Moshe heard Hashem's voice directly inside the Mishkan. This apparent contradiction is resolved by a third verse (Bamidbar ibid.), which states that Moshe would enter the Mishkan, whereupon he would hear Hashem's voice as it emanated from above the Aron.
This concept illustrates the dual nature of the Mishkan. The Mishkan served as a locus of Hashra'as Ha-Shechinah, where the intensity of Hashem's Presence was manifest; this is represented by Hashem's voice resonating from above the Aron. The Mishkan also served as a place where Man approached Hashem and drew near to Him; this is represented by Moshe entering the Mishkan to communicate with the Divine. The Sifri affirms that both visions of the Mishkan are accurate. This is why the Torah presents the Mishkan twice in its entirety, in both orders as explaned above, reflective of the two primary visions of the Mishkan, establishing the Mishkan's duality as a locus of Hashra'as Ha-Shechinah and also a place where Man appraoches God and draws close to Him.
May both of these concepts again be concretely manifest soon.