Cameron International (CAM.DL) and National Oilwell Varco (NOV 0.16%) are the market's most watched oil service companies. Both companies produce equipment for the offshore and onshore drilling industries, and their earnings and outlooks are often considered to be leading indicators for the oil services market.

However, both companies recently reported their first-quarter results and provided extremely different outlooks.

Strong quarter, strong outlook
Cameron reported a pretty strong first quarter all around. Indeed, earnings for the period came in at $0.75 per share, net of special items, while total revenue for the quarter came in at $2.4 billion, up 18% year on year.

At the end of the quarter, Cameron's order backlog sat at $11.2 billion, up 13% from the same period last year. However, the company only reported a net inflow of orders for the period of $2.5 billion, lower than the year-ago level, although the company attributed its poor performance to its OneSubsea subsidiary, which did not book any major projects during the quarter.

OneSubsea
A joint venture between Cameron and Schlumberger (SLB 0.26%) that delivers integrated solutions for the subsea oil and gas market, OneSubsea is actually one of Cameron's more interesting subsidiaries. The joint venture leverages Cameron's flow-control expertise, manufacturing, and aftermarket capabilities in combination with Schlumberger's technological innovations.

What's more, as oil majors seek to cut costs, improve recovery rates, and drive low-cost growth from their existing assets, OneSubsea is likely to become increasingly important for both Cameron and Schlumberger.

Cameron's management has reported that tendering activity for OneSubsea's services is at the highest level seen at any point during the last two years; there are several projects set to be awarded to the company during the next 18 or so months. Further, during the first quarter, a number of operators reached out to OneSubsea to assist them in efforts to improve reservoir recovery rates for existing fields. OneSubsea's revenue totaled $540 million in the first quarter, an increase of 60% versus year-ago levels.

Drilling outlook
Like peer National Oilwell Varco, Cameron had a strong quarter in terms of drilling systems ordered. However, unlike National Oilwell Varco, Cameron did not caution on its drilling systems outlook for the rest of the year. Actually, it did not comment much about its drilling systems outlook at all.

That being said, management did comment that, "In spite of the overall backdrop of slowing newbuild rig demand, Cameron had a very strong orders quarter in Q1 totaling $820 million, up 25% versus year-ago levels."

Drilling systems revenue jumped by 35% year on year during the quarter, and the drilling backlog stayed above $4 billion. Further, management reiterated the company's commitment to drive earnings growth within the drilling division by cutting costs.

However, National Oilwell Varco shocked some analysts when it reported first quarter results and revealed that it expected that the company's order backlog would fall in the region of $14 billion to $15 billion by the end of the year, down from a record high of $16.6 billion as reported at the end of the first quarter.

Still, this lower guidance does give the company some scope to surprise to the upside throughout the rest of the year.

With this in mind, as National Oilwell Varco is one of the largest players within the oil-services market, it would be reasonable to assume that similar factors will affect Cameron going forward.

Nevertheless, Cameron's management stated on the first-quarter conference call:

A lot of focus by this management team is being placed on improving our performance with the execution on the record backlog in Drilling Systems... see this show up in margin improvement as we progress through the year.

So if the deepwater drilling market slowdown does affect Cameron, then margin improvements are likely to offset some sales declines.

Meanwhile, Cameron continues to invest in its aftermarket services offering. The company plans to invest as much as $500 million back into its aftermarket services offering throughout the rest of 2014 to improve its aftermarket capabilities, serve its customers more efficiently, and broaden the company's footprint within growing markets.

This is great news, as aftermarket services provide predictable streams of recurring revenue for any company and help offset cyclical demand trends for equipment. This could help Cameron offset some of the softening in demand for drilling equipment that National Oilwell Varco is expecting to occur during the next few quarters.

Cameron's management is guiding for EPS of somewhere between $3.80 and $4.10 for fiscal 2014.

Foolish summary
Overall, even though National Oilwell Varco and Cameron are active within the same field, both companies have different outlooks. On one hand, National Oilwell Varco is forecasting a slowdown; on the other, Cameron is expecting to do more business as the company's OneSubsea joint venture meets an important need for the oil and gas industry. In addition, Cameron continues to cut costs in an attempt to improve profits and margins.